An approach for determination of lateral limit angle in kinematic planar sliding analysis for rock slopes

Planar sliding is one of the frequently observed types of failure in rock slopes.Kinematic analysis is a classic and widely used method to examine the potential failure modes in rock masses.The accuracy of planar sliding kinematic analysis is significantly influenced by the value assigned to the lateral limit angleγlim.However,the assignment ofγlim is currently used generally based on an empirical criterion.This study aims to propose an approach for determining the value ofγlim in deterministic and probabilistic kinematic planar sliding analysis.A new perspective is presented to reveal thatγlim essentially influences the probability of forming a potential planar sliding block.The procedure to calculate this probability is introduced using the block theory method.It is found that the probability is correlated with the number of discontinuity sets presented in rock masses.Thus,different values ofγlim for rock masses with different sets of discontinuities are recommended in both probabilistic and deterministic planar sliding kinematic analyses;whereas a fixed value ofγlim is commonly assigned to different types of rock masses in traditional method.Finally,an engineering case was used to compare the proposed and traditional kinematic analysis methods.The error rates of the traditional method vary from 45%to 119%,while that of the proposed method ranges between 1%and 17%.Therefore,it is likely that the proposed method is superior to the traditional one.

Novel Method for Spatial Angle Measurement Based on Rotating Planar Laser Beams

Spatial angle measurement, especially the measurement of horizontal and vertical angle, is a basic method used for industrial large-scale coordinate measurement. As main equipments in use, both theodolites and laser trackers can provide very high accuracy for spatial angle measurement. However, their industrial applications are limited by low level of automation and poor parallelism. For the purpose of improving measurement efficiency, a lot of studies have been conducted and several alternative methods have been proposed. Unfortunately, all these means are either low precision or too expensive. In this paper, a novel method of spatial angle measurement based on two rotating planar laser beams is proposed and demonstrated. Photoelectric receivers placed on measured points are used to receive the rotating planner laser signals transmitted by laser transmitters. The scanning time intervals of laser planes were measured, and then measured point＇s horizontal/vertical angles can be calculated. Laser plane＇s angle parameters are utilized to establish the abstract geometric model of transmitter. Calculating formulas of receiver＇s horizontal/vertical angles have been derived. Measurement equations＇ solvability conditions and judgment method of imaginary solutions are also presented after analyzing. Proposed method for spatial angle measurement is experimentally verified through a platform consisting of one laser transmitter and one optical receiver. The transmitters used in new method are only responsible for providing rotating light plane signals carrying angle information. Receivers automatically measure scanning time of laser planes and upload data to the workstation to calculate horizontal angle and vertical angle. Simultaneous measurement of multiple receivers can be realized since there is no human intervention in measurement process .Spatial angle measurement result indicates that the repeatable accuracy of new method is better than 10＂. Proposed method can improve measurement＇s automation degree and speed while ensuring measurement accuracy.

Dynamic strength of rock with single planar joint under various loading rates at various angles of loads applied

Intact rock-like specimens and specimens that include a single, smooth planar joint at various angles are prepared for split Hopkinson pressure bar（SHPB） testing. A buffer pad between the striker bar and the incident bar of an SHPB apparatus is used to absorb some of the shock energy. This can generate loading rates of 20.2-4627.3 GPa/s, enabling dynamic peak stresses/strengths and associated failure patterns of the specimens to be investigated. The effects of the loading rate and angle of load applied on the dynamic peak stresses/strengths of the specimens are examined. Relevant experimental results demonstrate that the failure pattern of each specimen can be classified as four types： Type A, integrated with or without tiny flake-off; Type B, slide failure; Type C, fracture failure; and Type D, crushing failure. The dynamic peak stresses/strengths of the specimens that have similar failure patterns increase linearly with the loading rate, yielding high correlations that are evident on semi-logarithmic plots. The slope of the failure envelope is the smallest for slide failure, followed by crushing failure, and that of fracture failure is the largest. The magnitude of the plot slope of the dynamic peak stress against the loading rate for the specimens that are still integrated after testing is between that of slide failure and crushing failure. The angle of application has a limited effect on the dynamic peak stresses/strengths of the specimens regardless of the failure pattern, but it affects the bounds of the loading rates that yield each failure pattern, and thus influences the dynamic responses of the single jointed specimen. Slide failure occurs at the lowest loading rate of any failure, but can only occur in single jointed specimen that allows sliding.Crushing failure is typically associated with the largest loading rate, and fracture failure may occur when the loading rate is between the boundaries for slide failure and crushing failure.

SCATTERING OF CIRCULAR CAVITY IN RIGHT-ANGLE PLANAR SPACE TO STEADY SH-WAVE

Complex function method and multi-polar coordinate transformation technology are used here to study scattering of circular cavity in right-angle planar space to SH-wave with out-of-plane loading on the horizontal straight boundary. At first, Green function of right-angle planar space which has no circular cavity is constructed; then the scattering solution which satisfies the free stress conditions of the two right-angle boundaries with the circular cavity existing in the space is formulated. Therefore, the total displacement field can be constructed using overlapping principle. An infinite algebraic equations of unknown coefficients existing in the scattering solution field can be gained using multi-polar coordinate and the free stress condition at the boundary of the circular cavity. It can be solved by using limit items in the infinite series which can give a high computation precision. An example is given to illustrate the variations of the tangential stress at the boundary of the circular cavity due to different dimensionless wave numbers, the location of the circular cavity, the loading center and the distributing range of the out-of-plane loading. The results show the efficiency and effectiveness of the mothod introduced here.

Beamforming and Angle-of-Arrival Estimation of Square Planar Antenna Array

This paper presents a dual-band planar antenna array for ISM band applications (2.4 GHz and 2.45 GHz). This antenna is proposed for indoor applications and enables adaptive beamforming and angle of arrival (AOA) estimation. An adaptive beamforming algorithm is applied for a planar antenna array, which is able to steer its main beam and nulls in azimuth and elevation planes over a wide frequency band. Planar antenna array operates as a spatial filter in 3D space, processing the received signals with weighting schemes. A planar antenna array is designed for AOA estimation in azimuth and elevation planes by using MUltiple SIgnal Classification (MUSIC) based on subspace algorithm. The Base Station (BS) equipped with this planar antenna is preferred to be at the center position on the room ceiling to cover all sectors of the room. It is designed to use four directional triangular elements arranged to form a square planar antenna array. Planar antenna with four elliptical slotted triangular elements (PAFESTE) is used to obtain optimal directivity in four directions in azimuth plane with specific orientation of 30? in elevation plane. It is characterized by half power beamwidth in elevation plane of about 60? and half power beamwidth in azimuth plane of about 90?.

View on the Clinical Value of QRS-T Angle

The QRS-T angle,as an index of noninvasive cardioelectric vector,is closely related to the change of heart structure and function.There are different methedologies to measure the QRS-T angle,which can be roughly dividedinto two types:plane angle and space angle.Studies show that the influence factors include two aspects of physiology and pathology of the angle,in pathological ways,the disease such as myocardial hypertrophy,myocardial ischemia,hypertension,ventricular arrhythmia has larger clinical significance.In recent years,the research on the risk stratification of the QRS-T angle on sudden death has made great progress,but there are still some disputes about whether the space angle can be replaced by the plane angle and the range of normal value and so on.

平面QRS-T夹角对陈旧性心肌梗死患者心功能不全的评估价值

目的通过分析体表心电图平面QRS-T夹角,从而探索一种陈旧性心肌梗死(简称心梗)心功能不全的心电图评估方法。方法回顾性分析本院住院的陈旧性心梗患者,心电图机自测QRS波向量与T波向量,计算出平面QRS-T夹角,测量各患者的左室射血分数(LVEF),分析两者之间的联系。结果 1000例陈旧性心梗患者,平面QRS-T夹角为88.5±50.6°。平面QRS-T夹角与LVEF负相关(r=-0.406,P(0.01),LVEF越低,相关越密切。分别以平面QRS-T夹角(80°、(90°、(100°为界定点进行分析,其中平面QRS-T夹角(90°诊断心功能不全的灵敏度和特异度最强(76%,74%)。结论平面QRS-T夹角与陈旧性心梗患者的LVEF呈负相关。

不同平面QRS-T夹角水平对陈旧性心肌梗死患者心功能不全的评估价值研究

目的研究不同平面QRS-T夹角水平对陈旧性心肌梗死患者心功能不全的评估价值。方法通过对我院2009年3月至2015年9月心内科就诊治疗的170例陈旧性心肌梗死患者临床资料做回顾性分析,比较两组不同心功能患者间的一般临床资料、不同QRS-T夹角(QRS-T夹角<50°、50°≤QRS-T夹角<70°、70°≤QRS-T夹角<90°和90°≤QRS-T夹角<100°及QRS-T夹角≥100°)所占比例及各组间WBC计数及CK-MB水平,并分析LVEF值和QRS-T夹角相关性。结果心功能不全组间WBC及CK-MB水平均较心功能正常组高,且平面QRS-T夹角<50°、90°≤QRS-T夹角<100°及QRS-T夹角≥100°在心功能正常和心功能不全组间比较差异有统计学意义(P<0.05),表明随着LVEF值的降低,QRS-T夹角越大,平面QRS-T夹角和LVEF值呈负相关关系,当LVEF<0.5时,相关系数r=-0.467,P<0.05,当LVEF<0.35时,相关系数r=-0.489,P<0.05。90°≤QRS-T夹角<100°和QRS-T夹角≥100°的灵敏度和特异度分别为95.32%、94.02%和96.98%和95.68%,与WBC、CK-MB及其他QRS-T夹角比较差异间均有统计学意义(P<0.05)。结论不同平面QRS-T夹角对于心功能不全的评估均存在一定的临床价值,且平面QRS-T夹角和LVEF值呈负相关关系,LVEF值越小,平面QRS-T夹角越大。当90°≤QRS-T夹角<100°和QRS-T夹角≥100°时灵敏度和特异度最高,两者间无明显差异,故当QRS-T夹角≥90°可作为临床上评估心功能不全的指标之一。

Orientation angle workspaces of planar serial three-link manipulators

This paper presents a classification on the workspaces of planar serial three-link manipulators, that is, position workspace and orientation angle workspace. Position workspace indicates the region reached by the reference point on the end-effector. Orientation angle workspace indicates a set of angle ranges by which the end-effector can reach with certain orientation for every point in the reachable position workspace. By introducing a virtual equivalent mechanism, reachable position workspace can be di- vided into several Grashof intervals and non-Grashof intervals. The calculation equations of orientation angle workspace are deduced in three situations according to the relationships among four link lengths in the virtual four-bar chain. Three examples are given for three kinds of relationship of link lengths. The orientation angle workspace of extended groups, that is, two of the three link lengths equal, and the orientation angle workspace when the reference point on the end-effector moves along a non-radial direction are also discussed. A program is developed to calculate orientation angle workspaces and output variation curves of orientation angle workspace and key data within the position workspace. The approach and program in this paper can be used for fast calculation and identification of the variation rule of the orientation angle workspace of any given planar serial three-link manipulator on the basis of its link parameters, and for the design of a highly dexterous serial manipulator with proposed link rela- tions.

Prognostic Significance of Frontal QRS-T Angle in Patients with Idiopathic Dilated Cardiomyopathy

Background： Current risk stratification of idiopathic dilated cardiomyopathy （IDC） lacks sufficient sensitivity and specificity. The objective of this study was to investigate the predictive role of frontal QRS-T angles in IDC. Methods： A prospective study with 509 IDC patients was performed from February 2008 to December 2013 in the Affiliated Drum Tower Hospital, Nanjing University School of Medicine. Baseline values and changes in QRS-T angles were recorded. Follow-up was conducted every 6 months. Analyses by Cox Proportional Hazards model were performed to evaluate the association between QRS-T angle and outcomes. The primary outcome of interest was all-cause mortality. Results： During a median follow-up of 34 months, 90 of 316 patients with QRS-T angles 〉90° died compared to 31 of 193 patients with QRS-T angles ≤90° （hazard ratio [HR] 2.4, P 〈 0.001）. Cardiac death was more prevalent in patients with a wide QRS-T angle （HR 2.4, P 〈 0.001）, similar to heart failure rehospitalization （HR = 2.5, P 〈 0.001）. After adjustment for potential prognostic factors, the QRS-T angle was independently associated with all-cause mortality （HR - 2.5, P 〈 0.05）, cardiac mortality （HR = 1.9, P 〈 0. 05）, and heart failure rehospitalization （HR = 2.3, P 〈 0.01）. Optimized therapy significantly narrowed the frontal QRS-T angle （100.9 ±53.4° vs. 107.2 ± 54.4°, P 〈 0.001 ）. The frontal QRS-T angle correlated well with established risk factors, such as left ventricular ejection fraction, brain natriuretic peptide, and New York Heart Association functional class. Conclusions; The frontal QRS-T angle is a powerful predictor of all-cause mortality, cardiac mortality, and worsening heart failure in IDC patients, independent of well-established prognostic factors. Optimized therapy significantly narrows the QRS-T angle, which might be an indicator of medication compliance, but this requires further investigation.

Orientation angle rotatability of planar serial n-link manipulators

This paper presents a new method of analyzing the orientation angle rotatability of a planar serial n-link manipulator by examining the rotatability of its virtual equivalent mechanism.Workspace orientation boundary region decomposition is proposed based on the polynomial discriminant derived from a serial three-link manipulator.Orientation angle workspace indicates a set of angle ranges by which the end-effector can reach with certain orientation for every point in the reachable position workspace.By introducing a virtual equivalent mechanism,the open-chain kinematic problem is converted into a close-chain mechanism,and the Grashof-type condition is used to examine the rotatability of the end-effector link.The reachable position workspace can be divided into several Grashof intervals and non-Grashof intervals based on the extreme positions and singular configurations of a manipulator.The derived equations in this paper can be used to calculate the variation rule of the orientation angle workspace of any given planar serial n-link manipulator on the basis of its link parameters.The orientation angle rotatability of a seven-link serial manipulator is solved by the proposed method and graphical representations of the orientation angle workspaces are mapped onto a three-dimensional coordinate system.The theoretical approach has practical significance for the design of a highly dexterous serial n-link manipulator with proposed link relations.

高速公路线形设计研究

高速公路线形设计是高速公路建设中的关键环节,其设计质量直接关系到道路的安全性、舒适性和经济性。论文阐述了高速公路线形设计的基本理论,包括高速公路线形设计基本概念、基本原则及影响因素,讨论了高速公路线形设计要点,包括平面线形、纵断面和平纵面设计。

基于PLIF的水平三向撞击流径向流型的研究

利用平面激光诱导荧光技术(PLIF)测量了水平三向撞击流反应器内液体混合时变化的二维浓度场,发现了其内部存在两种不同的径向流型:漏斗径向射流和自由径向射流。借助径向射流偏转角β对两种流型的变化规律进行了探索,实验结果表明等效喷嘴间距L*=1D时,偏转角变化范围Δβ很小;L*增大到2D时,Δβ急剧增大,出现峰值。当L*继续增大到3D、4D和5D时,Δβ略微下降,最终趋于稳定。流速u的变化对Δβ的影响较小。小喷嘴直径D工况下,最佳喷嘴间距为L*=2D或L*=3D;中等喷嘴直径D工况下,最佳喷嘴间距为L*=2D。通过计算离析度IOS得到完全混合所需时间t,发现Δβ越大,混合所需时间t越短,混合效果越好。

基于不同水压分布的平面滑动边坡稳定性研究

为研究地下水对平面滑动边坡的影响,归纳了平面滑动边坡常见的3种水压分布形式,并阐述了其分布假设的合理性。根据极限平衡理论,采用Matlab编制程序,通过有无张裂缝两个算例,定性与定量分析相结合,就不同滑动面水深、滑动面倾角、坡高、坡顶倾角、裂缝水平夹角等影响因子进行敏感性分析,重点探讨了在不同水压分布时影响因子对边坡安全系数影响的动态演绎规律。研究表明,平面滑动边坡临界倾角可通过极限平衡理论编制程序计算,并考虑地下水得出临界倾角变化趋势,取经验值10%为浮动范围;边坡影响因子对安全系数的影响随着地下水位的升高而变大,其中坡高对安全系数影响显著,坡顶倾角、张裂缝水平夹角和坡顶距张裂缝距离等对安全系数影响不明显。

平面连杆机构的急回特性与极位夹角的关系研究

急回平面连杆机构实现了机构工作行程的慢速进给和空回行程的快速退回 ,从而提高了生产率。而平面连杆机构的急回特性与其极位夹角θ密切相关。由于极位夹角θ是个锐角 ,现行的众多教科书中的行程速比系数k与极位夹角θ的关系式在应用上有一定的局限性。在本文给出的k与极位夹角θ的补充公式后解决了这个问题 。

裂缝性地层水力裂缝非平面延伸模拟

受天然裂缝作用影响,裂缝性地层的水力裂缝可能延伸为多分支、非平面的复杂裂缝体系,这与均质地层压裂产生的对称双翼平面裂缝具有巨大的差异。由于常规水力裂缝延伸模型无法用于模拟裂缝性地层中水力裂缝非平面延伸的裂缝形态和裂缝几何,为此,基于水力裂缝相交天然裂缝转向延伸路径的等效平面裂缝思想,建立了水力裂缝非平面转向延伸的数学模型,并推导了相应的数值求解方法。模拟计算表明,当水力裂缝沿天然裂缝转向延伸时,水力裂缝缝宽在延伸路径上表现为非连续分布,在转向延伸段突变减小,受缝宽减小节流效应影响,井底流体压力升高。影响因素分析表明,水平地应力差和逼近角越大,转向延伸段缝宽越小,对支撑剂输送限制越大;施工排量和压裂液黏度越高,包括转向延伸段在内,整个延伸裂缝段的缝宽越大,支撑剂在裂缝内的运移越容易,压裂施工风险越低。研究为认识裂缝性地层水力裂缝非平面延伸特征提供了思路和方法,为裂缝性地层压裂设计提供了理论依据,具有重要的理论价值和现实意义。

基于Arrhenius方程研究活性剂对铜CMP粗糙度的影响

选用非离子表面活性剂脂肪醇聚氧乙烯醚(AEO),通过自制的碱性铜抛光液,在E460E机台上研究不同体积分数活性剂对铜化学机械抛光(CMP)效果的影响。利用原子力显微镜(AFM)观察抛光后铜表面粗糙度,采用接触角测试仪测试不同的抛光液在铜表面的接触角。结果表明:铜抛光速率随着活性剂体积分数的增加呈缓慢降低趋势,加入活性剂可显著降低抛光后铜表面粗糙度。当加入体积分数3.0%的活性剂时,铜抛光速率从678.096 nm/min降低到625.638 nm/min,同时铜表面粗糙度从10.52 nm降低到1.784 nm,接触角从28.33°降低到12.25°。活性剂分子优先吸附在抛光后铜表面形成一层分子膜,表面粗糙度降低的根本原因是该分子膜增加了化学反应的活化能以及提高了抛光液的润湿性。基于Arrhenius方程,从活化能和温度两个参数阐述活性剂降低铜表面粗糙度的机制。

舵面角度测量中结构光光条图像自动定位方法

本文提出了一种在舵面角度测量中多平面结构光光条的自动定位方法。该方法首先基于Steger方法提取舵面中多个平面的光条图像中心;然后基于直线约束和距离约束提取出各小直线段,并根据各直线段的直线方向将各小直线段归类为最后的光条直线;最后根据光条直线的位置判断各光条直线所在光平面及所在舵平面。经实验验证,本文方法切实有效,具有较高的鲁棒性。

平面相控阵宽角扫描技术

宽角扫描技术是近年来平面相控阵研究领域的热点和难点。从2008年起,电子科技大学计算电磁学团队便开展了相关研究工作,提出了利用方向图可重构技术突破平面相控阵宽角扫描瓶颈的理论和实验方案,并逐步发展了基于电磁镜像原理、表面波辅助设计、磁流源技术、非周期阵列和时间反演自适应优化等理论和方法,用于实现平面相控阵宽角扫描。文章回顾了该团队在平面相控阵宽角扫描领域的研究历程,并对其研究发展做出展望。

镇泾地区延长组8段致密储层裂缝识别与预测

鄂尔多斯盆地镇泾地区延长组8段致密储层非均质性强，裂缝发育不均，给油气勘探、注水开发带来一系列的困难。根据镇泾地区延长组的岩心照片观察及常规测井、电成像测井资料研究，对地层的单井及平面展布特征进行了分析。结果表明，延长组长8段地层具低孔隙度低渗透率的特点，平均每口井发育裂缝3～6条，裂缝大多为高角度缝或垂直裂缝，其发育程度与电阻率的径向变化值、幅度差以及砂体厚度、砂层致密程度相关性显著。根据测井资料在单井裂缝识别的基础上，结合砂体展布、沉积相分布特征对该区长8段裂缝发育情况进行了平面展布预测，为该区油气勘探、开发奠定了基础。