Velocity-Free MS/AE Source Location Method for Three-Dimensional Hole-Containing Structures

Microseismic/acoustic emission(MS/AE)source localization method is crucial for predicting and controlling of potentially dangerous sources of complex structures.However,the locating errors induced by both the irregular structure and pre-measured velocity are poorly understood in existing methods.To meet the high-accuracy locating requirements in complex three-dimensional hole-containing structures,a velocity-free MS/AE source location method is developed in this paper.It avoids manual repetitive training by using equidistant grid points to search the path,which introduces A*search algorithm and uses grid points to accommodate complex structures with irregular holes.It also takes advantage of the velocity-free source location method.To verify the validity of the proposed method,lead-breaking tests were performed on a cubic concrete test specimen with a size of 10 cm10 cm10 cm.It was cut out into a cylindrical empty space with a size of/6cm10 cm.Based on the arrivals,the classical Geiger method and the proposed method are used to locate lead-breaking sources.Results show that the locating error of the proposed method is 1.20 cm,which is less than 2.02 cm of the Geiger method.Hence,the proposed method can effectively locate sources in the complex three-dimensional structure with holes and achieve higher precision requirements.

Solution and simulation algorithm of microseismic events location to three-dimensional model by comprehensive location method based on Matlab

The essential for microseismic monitoring is fast and accurate calculation of seismic wave source location. The precision of most traditional microseismic monitoring processes of mines, using TDOA location method in two-dimensional space to position the microseismic events, as well as the accuracy of positioning microseismic events, may be reduced by the two-dimensional model and simple method, and ill-conditioned equations produced by TDOA location method will increase the positioning error. This article, based on inversion theory, studies the mathematical model of TDOA location method, polariza- tion analysis location method, and comprehensive difference location method of adding angle factor in the traditional TDOA location method. The feasibility of three methods is verified by numerical simulation and analysis of the positioning error of them. The results show that the comprehensive location method of adding angle difference has strong positioning stability and high positioning accuracy, and it may reduce the impact effectively about ill-conditioned equations to positioning results. Comprehensive location method with the data of actual measure may get better positioning results.

Three-dimensional morphometric analysis for hepatectomy of centrally located hepatocellular carcinoma:A pilot study

AIM: To describe a three-dimensional model(3DM) to accurately reconstruct anatomic relationships of centrally located hepatocellular carcinomas(HCCs).METHODS: From March 2013 to July 2014, reconstructions and visual simulations of centrally located HCCs were performed in 39 patients using a 3D subject-based computed tomography(CT) model with customdeveloped software. CT images were used for the 3D reconstruction of Couinaud's pedicles and hepatic veins, and the calculation of corresponding tumor territories and hepatic segments was performed using Yorktal DMIT software. The respective volume, surgical margin, and simulated virtual resection of tumors were also estimated by this model preoperatively. All patients were treated surgically and the results were retrospectively assessed. Clinical characteristics, imaging data, procedure variables, pathologic features, and postoperative data were recorded and compared to determine the reliability of the model.RESULTS: 3D reconstruction allowed stereoscopic identification of the spatial relationships between physiologic and pathologic structures, and offered quantifiable liver resection proposals based on individualized liver anatomy. The predicted values were consistent with the actual values for tumor mass volume(82.4 ± 109.1 m L vs 84.1 ± 108.9 m L, P = 0.910), surgical margin(10.1 ± 6.2 mm vs 9.1 ± 5.9 mm, P = 0.488), and maximum tumor diameter(4.61 ± 2.16 cm vs 4.53 ± 2.14 cm, P = 0.871). In addition,the number and extent of portal venous ramifications, as well as their relation to hepatic veins, were visualized. Preoperative planning based on simulated resection facilitated complete resection of large tumors located in the confluence of major vessels. And most of the predicted data were correlated with intraoperative findings.CONCLUSION: This 3DM provides quantitative morphometry of tumor masses and a stereo-relationship with adjacent structures, thus providing a promising technique for the management of centrally located HCCs.

Three dimensional velocity structure and accurate earthquake location in Changning–Gongxian area of southeast Sichuan

In order to understand the crustal structure and tectonic background of the Changning–Gongxiang area, southeastern Sichuan Province, where a series of moderate-to-strong earthquakes occurred in recent years, we utilized the seismic phase data both from a local dense array and from the regional seismic networks;we used the tomoDD program to invert for the high-resolution three-dimensional velocity structure within the depth range of 0–10 km and for accurate hypocentral locations in this area. We analyzed the seismogenic structures for the events of Xingwen M5.7 in 2018 and Gongxian M5.3 and Changning M6.0 in 2019. The results show that:(1) widespread lateral inhomogeneity exists in the velocity structure of the study area, and the location of the velocity anomaly is largely consistent with known structures. In the range of distinguishable depth, the inhomogeneity decreases with increasing depth, and the velocity structure anomalies in some areas are continuous in depth;(2) earthquakes occurred in clusters, showing the characteristics of zonal folding trends in the NW-SE and NE-SW directions;the focal depth in the area is generally shallow in both the sedimentary cap and the crystalline basement. The seismogenic structures of small earthquake clusters are different in size and occurrence in different sections, and the clusters occurred mostly in regions with high P-or S-wave velocities;(3) synthesis of a variety of data suggests that the seismogenic structures of the Xingwen M5.7 and Changning M6.0 earthquakes are associated with slip faults that trend NW-SE in, respectively, the south wing and the axis of the Changning–Shuanghe anticline, while that of the Gongxian M5.3 earthquake is associated with thrust faults that trend N-S in the Jianwu syncline region. The dynamic sources of the three earthquakes are all from the SE pushing of the Qinghai–Tibet block on the Sichuan basin;(4) the risk of future strong earthquakes in this area must be reevaluated in light of the facts(a)that in recent years, moderate-to-strong earthquake swarms have occurred frequently in southeast Sichuan;(b) that the complex structural area exhibits the easy-to-trigger characteristic, and(c) that the small-scale faults in this area are characterized by the phenomenon of stress "lock and release".

Three-dimensional visualization of the functional fascicular groups of a long-segment peripheral nerve

The three-dimensional（3D） visualization of the functional bundles in the peripheral nerve provides direct and detailed intraneural spatial information. It is useful for selecting suitable surgical methods to repair nerve defects and in optimizing the construction of tissue-engineered nerve grafts. However, there remain major technical hurdles in obtaining, registering and interpreting 2D images, as well as in establishing 3D models. Moreover, the 3D models are plagued by poor accuracy and lack of detail and cannot completely reflect the stereoscopic microstructure inside the nerve. To explore and help resolve these key technical problems of 3D reconstruction, in the present study, we designed a novel method based on re-imaging techniques and computer image layer processing technology. A 20-cm ulnar nerve segment from the upper arm of a fresh adult cadaver was used for acetylcholinesterase（ACh E） staining. Then, 2D panoramic images were obtained before and after ACh E staining under the stereomicroscope. Using layer processing techniques in Photoshop, a space transformation method was used to fulfill automatic registration. The contours were outlined, and the 3D rendering of functional fascicular groups in the long-segment ulnar nerve was performed with Amira 4.1 software. The re-imaging technique based on layer processing in Photoshop produced an image that was detailed and accurate. The merging of images was accurate, and the whole procedure was simple and fast. The least square support vector machine was accurate, with an error rate of only 8.25%. The 3D reconstruction directly revealed changes in the fusion of different nerve functional fascicular groups. In conclusion. The technique is fast with satisfactory visual reconstruction.

多分辨剪枝局部聚类算法挖掘空间co-location模式

传统的co-location模式挖掘算法采取对各个特征实例进行逐一连接的挖掘方式,其结果是,常常消耗大量的时间和空间资源,甚至由于内存资源被过度消耗而无法挖掘出最终结果,特别是在数据量大的情况下更是如此。因此,提出了一种高效的多分辨剪枝局部聚类算法(MP_LC)。MP_LC算法首先对数据区域划分网格,再对各个网格中每一特征的实例进行聚类,求出每一类所包含实例的质心,用质心代替相应的实例集,并进行后续的挖掘。大量实验结果表明,MP_LC算法具有较高的效率、较高的准确率以及较好的实际应用价值。

Subpixel Target Location Techniques for 3-D Coordinate Measuring System

the close photogrammetric 3-D coordinate measurement is a newmeasuring technology in the fields of the coordinate measurementmachine (CMM) in recent years. In this method, we usually place sometargets on the measured object and take image of targets to determinethe object coordinate. The subpixel location of target image plays animportant role in high accuracy 3-D coordinate measuring procedure.In this paper, some subpixel location methods are reviewed and somefactors which affect location precision are analyzed.

The MW5.5 earthquake on August 6,2023,in Pingyuan,Shandong,China:A rupture on a buried fault

On August 6,2023,a magnitude MW5.5 earthquake struck Pingyuan County,Dezhou City,Shandong Province,China.This event was significant as no large earthquakes had been recorded in the region for over a century,and no active fault had been previously identified.This study collects 1309 P-wave arrival times and 866 S-wave arrival times from 74 seismic stations less than 200 km to the epicenter to constrain the spatial distribution of the mainshock and its 125 early aftershocks by the double difference earthquake relocation method,and selects 864 P-waveforms from 288 stations located within 800 km of the epicenter to constrain the focal mechanism solution of the mainshock through centroid moment tensor inversion.The relocation and the inversion indicate,the Pingyuan MW5.5 earthquake was caused by a rupture on a buried fault,likely an extensive segment of the Gaotang fault.This buried fault exhibited a dip of approximately 75°to the northwest,with a strike of 222°,similar to the Gaotang fault.The rupture initiated at the depth of 18.6 km and propagated upward and northeastward.However,the ground surface was not broken.The total duration of the rupture was~6.0 s,releasing the scalar moment of 2.5895×1017 N·m,equivalent to MW5.54.The moment rate reached the maximum only 1.4 seconds after the rupture initiation,and the 90%scalar moment was released in the first 4.6 s.In the first 1.4 seconds of the rupture process,the rupture velocity was estimated to be 2.6 km/s,slower than the local S-wave velocity.As the rupture neared its end,the rupture velocity decreased significantly.This study provides valuable insights into the seismic characteristics of the Pingyuan MW5.5 earthquake,shedding light on the previously unidentified buried fault responsible for the seismic activity in the region.Understanding the behavior of such faults is crucial for assessing seismic hazards and enhancing earthquake preparedness in the future.

基于RSSI的修正补偿三边定位算法设计与仿真

在无线传感器网络节点定位过程中,三边定位算法常结合测距算法获取未知节点的位置信息。针对现有三边定位算法定位精度低、适用范围小和需要多次发送定位数据包导致节点能耗增大等问题,提出一种修正补偿测量距离的三边定位算法。相比常见发送多次定位数据包然后进行滤波计算降低定位误差的方法,采用对数常态-模型测量节点间距离,发送较少定位数据包,通过判断三锚节点圆的相对位置,对由于测距误差较大导致节点圆不相交的3种情况进行修正补偿,采用基于质心算法的三边定位算法计算未知节点坐标。通过搭建Matlab仿真试验,验证算法可行性及定位精度,试验结果表明,提出的修正补偿三边定位算法综合考虑了定位精度、算法复杂度和节点功耗3者之间的关系,适用范围更广,定位误差<15%。

一种真空深低温下的红外光斑定位算法

红外光斑中心定位是红外光学测量的关键技术一,针对红外光斑分辨率低、对比度差、目标边缘模糊和光斑定位精度低等问题,提出了一种具有高精度小尺寸的红外光斑定位算法。对于红外图像前处理从单一滤波和组合滤波进行图像的前处理,之后通过红外光斑质心法和形心法确定光斑中心所在的亚像素级坐标。结果表明:在有噪声污染的红外光斑图像中,与其他算法相比,本算法误差小于0.035个像素,保证了红外光板的高精度定位。

基于质心−凸包−自适应聚类法的浮选泡沫动态特征提取

面对复杂的浮选现场环境及浮选泡沫自身相互粘连导致的边界不清等情况,现有泡沫动态特征(流动速度和崩塌率)提取方法往往无法准确划定属于每个泡沫的动态特征采样区域、不能全面匹配相邻帧间的特征点对且难以有效识别崩塌区域。针对上述问题,提出了一种基于质心−凸包−自适应聚类法的浮选泡沫动态特征提取方法。该方法采用集成Swin−Transformer多尺度特征提取能力的改进型Mask2Former,实现对泡沫质心的精准定位和崩塌区域的有效识别;通过最优凸包评价函数搜寻目标泡沫周围相邻一圈泡沫质心构建的凸包,拟合出接近实际泡沫轮廓的动态特征采样区域;运用基于Transformer的局部图像特征匹配(LoFTR)算法匹配相邻帧图像间的特征点对;针对动态特征采样区域内部的所有特征点对,通过基于OPTICS算法的主特征自适应聚类法提取每个泡沫的主要流动速度。实验结果表明,在普通泡沫质心定位和崩塌区域识别任务中,该方法分别取得了88.83%,97.92%的准确率及77.90%,96.52%的交并比;以2.69%的平均剔除率实现了99.93%的特征点对匹配正确率;在多种工况下均能有效划定与实际泡沫边界相近的特征采样区域,进而定量提取每个泡沫的动态特征。

基于冗余天线阵列和加权质心算法的光伏系统直流电弧故障定位方法

针对光伏直流电弧故障定位问题,本文通过研究故障电弧的电磁辐射特性,提出一种基于冗余天线阵列和加权质心算法的定位方法。先计算电弧燃烧时天线采集到的电磁信号的方均根值,与辐照度一起输入BP神经网络预测天线与电弧的距离;再构造冗余天线阵列研究不同天线数量和布局方式,选出接收信号最强的天线,将天线坐标和距离输入加权质心算法,获得定位结果;最后结合K均值聚类算法提高定位精度。实验结果表明,所提方法具有良好的定位能力。

Refocusing and locating effect of fluorescence scattering field

Optical imaging deep inside scattering medium has always been one of the challenges in the field of bioimaging,which significantly drawbacks the employment of con-focal microscopy system.Although a variety of feedback techniques,such as acoustic or nonlinear fluorescence-based schemes have realized the refocusing of the coherent light,the problems of non-invasively refocusing and locating of linearly-excited fluorescent beads inside the scattering medium have not been thoroughly explored.In this paper,we linearly excited the fluorescent beads inside a scattering medium by using our homemade optical con-focal system,collected the fluorescence scattering light as the optimized target,and established a theoretical model of target contrast enhancement,which is consistent with the experimental data.By improving both the cost function and variation rate within the genetic algorithm,we could refocus the fluorescence scattering field while improving the contrast enhancement factor to 12.8 dB.Then,the positions of the fluorescent beads are reconstructed by subpixel accuracy centroid localization algorithm,and the corresponding error is no more than 4.2μm with several fluorescent beads within the field of view.Finally,the main factors such as the number of fluorescent beads,the thickness of the scattering medium,the modulating parameter,the experimental noise and the system long-term stability are analyzed and discussed in detail.This study proves the feasibility of reconstructing fluorescent labeled cells inside biological tissues,which provides certain reference value for deep imaging of biological tissues.

基于权重系数自调整的加权质心定位算法

针对目前采用的经典加权质心定位算法,其定位节点的位置的精确度较低。文章通过RSSI测距结合加权定位提出一种基于权重系数自调整的加权质心定位算法。该算法进行多个节点位置的估算时采用经典质心算法,之后对多个估计位置利用优化权值的方法进行求值,最后明确节点位置所在。该算法是融合了RSSI测距的技术和经典质心算法的加权算法,操作更为容易。经过进行仿真实验,可以看出与经典的定位算法相比,该算法定位的精确度有比较明显的提升。

基于WiFi-蓝牙混合定位技术的震后压埋人员手机定位方法

我国地震灾害频发,快速确定压埋人员的准确位置成为震后救援工作的一大难点。文中提出的基于WiFi-蓝牙混合定位技术的震后压埋人员手机定位方法,通过在模拟的震后压埋环境周边分别部署WiFi探针和蓝牙网关,采集压埋人员携带的智能设备发射的信号接收强度(received signal strength indication, RSSI)数据,利用高斯-卡尔曼混合滤波对RSSI数据进行预处理,建立基于震后压埋环境的无线信号距离损耗模型,采用改进的加权质心定位算法解算压埋智能设备的坐标,通过评估WiFi和蓝牙定位结果可信度确定最终的定位结果。实验结果表明:单一的WiFi定位技术和蓝牙定位技术的平均定位精度分别为0.917、0.867 m,而WiFi-蓝牙混合定位技术的定位精度为0.541 m,相对于单一的WiFi和蓝牙定位技术,定位精度分别提高了41%和37.6%。

一种基于交点质心求解的RSSI定位算法及其优化

为了提高RSSI算法的定位精度,提出了一种新的基于交点质心求解的RSSI算法.此方法用矩阵求解多组二元二次方程组,得出的结果为这些方程组解的平均值,定位坐标由这些平均值确定.相比于传统最小二乘法,交点质心法的定位精度明显提高,并给出了两种优化方案,最后提出了一种实现三维定位的方法.

基于双目立体视觉技术的成熟番茄识别与定位

研究了基于双目立体视觉技术的成熟番茄的识别与定位方法,获取了成熟番茄的位置信息,用于指导温室内成熟番茄的自动化采摘作业。该方法利用成熟番茄与背景之间颜色特征的差异进行图像分割来识别成熟番茄;根据图像分割的结果,用形心匹配方法获取番茄中心的位置;然后根据相邻区域像素点灰度的相关性,利用区域匹配方法计算番茄表面各点的深度信息。使用限制候选区域和两次阈值分割的方法减少计算量,提高了计算精度。实验结果表明,工作距离小于550mm时,番茄深度值的误差约为±15mm。利用该测量方法可以实现成熟番茄位置信息的获取,测量精度较高。

光斑质心亚像素定位误差的实验研究

根据误差的来源将光斑质心亚像素定位误差归类为随机误差和系统误差,提出一种简单有效的实验方法对光斑质心定位误差进行定量测试。利用高精度一维电动平移台、POINTGREYFlea2-14S3CCD相机和LED光源构建了测试系统,对测试结果进行研究和讨论,发现了测试系统LED光斑质心定位系统误差的周期性变化规律,计算得到了基于Flea2-14S3CCD相机的光斑质心定位随机误差为0.018pixels,系统误差为0.06pixels,总体误差为0.063pixels(约1/15pixels),能够应用于以光斑质心检测为手段的测量系统中。实验表明,该测试系统可以作为估算光斑质心定位误差大小的一种有效的手段。

一种改进的加权质心定位算法

针对无线传感器网络质心定位算法精度不高的问题,提出了一种利用信号强度比值的加权质心定位算法(RR-WCL).系统中的信标节点周期性地发送自身信息,未知节点在收到信标节点的信息之后只记录同一个信标节点的信号强度均值,在收到超过阈值的信标信息后,建立信标节点集合、信号强度集合和信标节点位置集合,最后将未知节点接收到的信标节点信号强度的比值作为加权因子进行定位.仿真和真实系统实验结果表明,RR-WCL算法在不同环境下表现稳定,随着信标节点数目的增加,与质心算法相比,其定位精度可提高6.4%～37.25%,与加权质心算法相比,其定位精度可提高5.12%～11.23%.

基于能量累加的空间目标星像质心定位

研究了CCD观测图像的亚像素级高精度质心定位方法以提高目标星像的天文定位精度。分析了影响定位精度的主要因素,如图像噪声、离散化采样误差及定位窗口选择等,结合CCD弥散斑的成像特性,提出了一种基于能量累加的空间目标星像质心定位方法。该方法使用插值方式降低离散采样点和实际感光区域光线照度的不一致性;利用弥散斑能量累加自适应地确定目标星像的有效窗口,优化目标星像灰度,消除随机噪声的影响;并采用平方加权质心定位方法进行质心计算。实验结果表明,该方法具有较强的抗干扰能力和稳定性,定位精度可达0.01pixel,适用于低信噪比条件下的质心定位计算。