Analysis on the master event method and precise location of 1997 Jiashi strong earthquake swarm in western China

Master event location method was described in detail in this paper. Some problems in the application of master event method have been analyzed and some improvements of the method have been made. As compared the location results of MS>=3.0 earthquakes of Jiashi swarm obtained by using this method with that by the traditional absolute method, the result obtained by using the master event method shows more reasonable and more consistent with that from the focal mechanism solutions. After relocation, we can see, the epicenters of M>=5.0 earthquakes show an echelon-type alignment along NNW-SSE direction, and all earthquakes concentrate nearly in a volume region about 30 km (N-S) × 15 km (E-W) × 15 km (U-D). Earthquake focal depths are mainly in the range of 15-28 km.

Improvements in seismic event locations in a deep western U.S. coal mine using tomographic velocity models and an evolutionary search algorithm

Methods of improving seismic event locations were investigated as part of a research study aimed at reducing ground control safety hazards. Seismic event waveforms collected with a 23-station three-dimensional sensor array during longwall coal mining provide the data set used in the analyses. A spatially variable seismic velocity model is constructed using seismic event sources in a passive tomographic method. The resulting three-dimensional velocity model is used to relocate seismic event positions. An evolutionary optimization algorithm is implemented and used in both the velocity model development and in seeking improved event location solutions. Results obtained using the different velocity models are compared. The combination of the tomographic velocity model development and evolutionary search algorithm provides improvement to the event locations.

Application of micro-seismic monitoring technology in mining engineering

Micro-seismic phenomena, occurring when rock masses are subjected to forces and failures, allow the determination of their unstable states and failure zones by analyzing micro-seismic signals. We first present the principles of micro-seismic monitoring and location, as well as an underground explosion-proof micro-seismic monitoring system. Given a practical engineering application, we describe the application of micro-seismic monitoring technology in determining the height of a "two-zone" overburden, i.e., a caving zone and a fracture zone, the width of a coal-pillar section and the depth of failure of a floor. The workfaces monitored accomplished safe and highly efficient mining based on our micro-seismic monitoring results and provide direct proof of the reliability and validity of micro-seismic monitoring technology.

Fast Marching Method for Microseismic Source Location in Cavern-Containing Rockmass: Performance Analysis and Engineering Application

Microseismic(MS)event locations are vital aspect of MS monitoring technology used to delineate the damage zone inside the surrounding rock mass.However,complex geological conditions can impose significantly adverse effects on the final location results.To achieve a high-accuracy location in a complex cavern-containing structure,this study develops an MS location method using the fast marching method(FMM)with a second-order difference approach(FMM2).Based on the established velocity model with three-dimensional(3D)discrete grids,the realization of the MS location can be achieved by searching the minimum residual between the theoretical and actual first arrival times.Moreover,based on the calculation results of FMM2,the propagation paths from the MS sources to MS sensors can be obtained using the linear interpolation approach and the Runge–Kutta method.These methods were validated through a series of numerical experiments.In addition,our proposed method was applied to locate the recorded blasting and MS events that occurred during the excavation period of the underground caverns at the Houziyan hydropower station.The location results of the blasting activities show that our method can effectively reduce the location error compared with the results based on the uniform velocity model.Furthermore,the obtained MS location was verified through the occurrence of shotcrete fractures and spalling,and the monitoring results of the in-situ multipoint extensometer.Our proposed method can offer a more accurate rock fracture location and facilitate the delineation of damage zones inside the surrounding rock mass.

An improved multidirectional velocity model for micro-seismic monitoring in rock engineering

An improved multidirectional velocity model was proposed for more accurately locating micro-seismic events in rock engineering. It was assumed that the stress wave propagation velocities from a micro-seismic source to three nearest monitoring sensors in a sensor's array arrangement were the same. Since the defined objective function does not require pre-measurement of the stress wave propagation velocity in the field, errors from the velocity measurement can be avoided in comparison to three traditional velocity models. By analyzing 24 different cases, the proposed multidirectional velocity model iterated by the Simplex method is found to be the best option no matter the source is within the region of the sensor's array or not. The proposed model and the adopted iterative algorithm are verified by field data and it is concluded that it can significantly reduce the error of the estimated source location.

RFID Complex Event Processing: Applications in Real-Time Locating System

Complex event processing (CEP) can extract meaningful events for real-time locating system (RTLS) applications. To identify complex event accurately in RTLS, we propose a new RFID complex event processing method GEEP, which is based on the timed automata (TA) theory. By devising RFID locating application into complex events, we model the timing diagram of RFID data streams based on the TA. We optimize the constraint of the event streams and propose a novel method to derive the constraint between objects, as well as the constraint between object and location. Experiments prove the proposed method reduces the cost of RFID complex event processing, and improves the efficiency of the RTLS.

Micro-earthquakes “Just-underneath” Seismic Stations as Ground Truth Events——Application to the 2008 Wenchuan Aftershock Sequence

Analyzing the aftershock sequence of the 2008 Wenchuan earthquake,we considered 26 micro-earthquakes "just underneath" seismic stations.Making use of such special station-event configurations to determine the depth of these micro-earthquakes provided accurate relocation of aftershocks with a reference set of "ground truth(GT)events".

Location Attractiveness as a Major Factor in Museum Visitors＇Choice and Satisfaction

This paper is intended to give a contribution to the debate on the functional relationship between the museum and the local territory; more specifically, the aim of this study is to understand the role of a museum location in attracting visitors and influencing their processes of choice and satisfaction. The study follows, in particular, a previous study conducted by Mariani and Mussini （2013） based on Fondazione di Venezia data, with a view to better contextualization level. Previous studies have examined the role of museums in enhancing the image of a destination and in attracting and conveying additional tourists＇ fluxes, arguing that although not all museums are a destination of choice for visitors, a great museum or a strong exhibition program still does represent a national and international attraction. This paper overturns this argument investigating whereas an appealing location （such as a tourist destination） can influence prospective visitors about the level of attractiveness of a pay cultural event taking place therein. A questionnaire was developed and data were collected at the Palazzo Ducale in Venice, Italy, in 2007, during the art exhibition ＂Venezia e l＇Islam 829-1797＂, via 501 face-to-face visitors interviews. The research model analyzes data through the conjoint analysis and the descriptive statistics. Results show that the exhibition location has been a relevant factor in influencing the visitors＇ decision process linked to the attendance of the event. Data show that, for the majority of visitors, the exhibition had been located elsewhere, they would not have visited it. Thus, an appealing location or a structured tourist destination may function as an attractive platform that may contribute to enforce the overall visitor＇s satisfaction with regard to his or her attendance to a cultural event. Furthermore, such a fact depends on specific objective variables （e.g., level of education, age）, although no significant differences were reported between segments based on other socio-demographic characteristics such as sex. To conclude, arts and cultural managers should market and position cultural events in locations that can function as attractive, thus as emotionally driven experience consumption sites. Furthermore, they should consider both the cognitive and the emotional aspects of visitor＇s experience when designing and planning their events, as well as when assessing visitor＇s satisfaction. Cognitive and emotional aspects should be considered simultaneously when measuring visitors＇ satisfaction. In shaping visitors＇ satisfaction, emotions, such as the pleasure to be in a particular location, are more significant than cognitive aspects, such as the theme of the exhibition.

Discussion on the Precise Relocation and Seismo-Tectonics of the Jiujiang-Ruichang Earthquake

Based on relocating the Jiujiang-Ruichang earthquake sequence which occurred on November 26, 2005 in Jiangxi Province with the double-difference （DD） algorithm and master event technique, the paper discusses the focal mechanism of the main shock （MsS.7） and the probable seismo-tectonics. The precise relocation results indicate that the average horizontal error is 0.31kin in a EW direction and 0.40kin in a NS direction, and the average depth error is 0.48kin. The focal depths vary from 8kin to 14kin, with the predominant distribution at 10kin - 12kin. The epicenter of the main shock is relocated to be 29.69^oN, 115.74^oE and the focal depth is about 10.Skin. Combining the predominant distribution of the earthquake sequence, the focal mechanism of the main shock and the tectonic conditions of N-E- and NW-strike faults growth in the seismic region, we infer that the main shock of the earthquake sequence was caused by a NW striking buried fault in the Rnichang basin. The nature of seismic faults needs to be further explored.

Relocating ruptures of two M6 earthquakes in Zhongba, South-central Tibet in 2004 and 2005 with seismological and geodetic methods

To better understand repeatability of strong earthquakes in previously ruptured zones during one seismogenic period, we studied the rupture zones of the doublet of M6 earthquakes in Zhongba region of southcentral Tibet, China, in 11 July 2004 and 7 April 2005, respectively. We focused on the overlapping degree of two strong quakes’ aftershock areas one week after the mainshocks by using the SQH station in China Seismic Network and a 68-stations temporary broadband seismic array, a part of the international HI-CLIMB project. About 115 local earthquakes were recorded in one week after the mainquakes, and we located these earthquakes by master event relative location （MERL） method. We also used this method to relocate 31 other M3.7 ＋ earthquakes from 1 July 2004 to 1 July 2005. Meanwhile, we studied two mainshocks’ coseismic ruptures with satellite interferometric synthetic aperture radar （InSAR）. Our results show that the ruptured zones of the two earthquakes do not overlapp substantially, either from early aftershock data or from InSAR inversions.

Discovering Event Regions Using a Large-Scale Trajectory Dataset

The city is facing the unprecedented pressure with the rapid development and the moving population. Some hidden knowledge can be found to service the social with human trajectory data. In this paper, we define a state-ofthe-art concept on fluctuant locations with PCA method and discover the same attribute of fluctuant locations called event with topic model. In the time slice, locations with the same attribute are called event region. Event regions aim to understand the relationship between spatial-temporal locations in the city and to early-warning analyze for the city planning, construction, intelligent navigation, route planning and location based service. We use GeoLife public data to experiment and verify this paper.

基于优化第三代非支配排序遗传算法的城市应急设施模糊选址

以杭州市上城区2022年全年核酸检测点记录数据为基础,采用优化型第三代非支配排序遗传算法(NSGA3),将杭州市上城区划分为10786个50 m×50 m的人口点,模拟每个人口点去往周边核酸检测这一聚集性应急行为,并进行50000次迭代.将迭代结果进行核密度分析,分别得出基于单设施点的15 min生活圈优化结果、基于双设施点的15 min生活圈优化结果、基于适老化需求修正的设施点优化结果,以及基于单设施点的5 min生活圈优化结果.结果显示,以单设施点的15 min生活圈优化结果为例,在不改变服务能力的前提下,基于优化NSGA3迭代后的核酸检测点网络,将设施平均可达时间从292.44 s优化到了264.62 s.基于核酸检测这一行为结果形成城市应急设施的模糊选址范围,得出“小集聚-大分散”空间规律;在此基础上将模糊选址范围转化为“社区级多功能应急空间”,为将来发生应急事件,进行临时应急设施选点决策时提供理论建议.

IPv6网络攻击事件溯源中的攻击树节点特征定位

在网络普及的现代,各类网络协议层出不穷,而在当下最为普遍的便是IPv6网络协议,其虽然优化解决了前网络协议中存在的部分问题,但是依旧存在各类安全隐患,为了能更好地预防并构建网络防御系统,需要对过往攻击事件中的攻击树节点特征实施提取。为此,提出了IPv6网络攻击事件溯源中的攻击树节点特征定位。该方法首先利用攻击类型实施扩展,得到攻击树模型,并以此展开计算,之后结合深度学习网络对攻击树的节点特征实施提取,最后利用DV-Hop方法对提取到的攻击树节点特征实施定位。所提方法在定位过程中不仅能耗低,而且误差小,不易受环境干扰,定位稳定性较好,定位效率较高,可以更有效地为改进网络防御系统提供数据支持。

Fracture evolution around pre-existing cylindrical cavities in brittle rocks under uniaxial compression

The development of fracture around pre-existing cylindrical cavities in brittle rocks was examined using physical models and acoustic emission technique. The experimental results indicate that when granite blocks containing one pre-existing cylindrical cavity are loaded in uniaxial compression condition, the profiles of cracks around the cavity can be characterized by tensile cracking （splitting parallel to the axial compression direction） at the roof-floor, compressive crack at two side walls, and remote or secondary cracks at the perimeter of the cavity. Moreover, fracture around cavity is size-dependent. In granite blocks containing pre-existing half-length cylindrical cavities, compressive stress concentration is found to initiate at the two sidewalls and induce shear crack propagation and coalescence. In granite blocks containing multiple parallel cylindrical cavities, the adjacent cylindrical cavities can influence each other and the eventual failure mode is determined by the interaction of tensile, compressive and shear stresses. Experimental results show that both tensile and compressive stresses play an important role in fracture evolution process around cavities in brittle rocks.

2002年夏季长白山天池火山区的地震活动研究

20 0 2年6月以来,长白山天池火山区的地震活动明显增加.本文利用2 0 0 2年夏季布设在长白山天池火山区15套宽频带流动地震台站的记录资料,对天池火山区的地震活动进行了研究.地震观测结果表明,2 0 0 2年夏季长白山天池火山日平均地震发生频次超过30次.地震主要位于长白山天池西南部和东北部两个区域,震源深度较浅,离地表的深度一般小于5km .天池西南部和东北部的地震,b值存在较大的差异.火山区地震记录的频谱分析和时频分析结果表明,这些地震主要为火山构造型地震.HSZ和DZD等台站地震记录中丰富的低频成分,可能与台站附近的局部介质或断层带有关.我们认为2 0 0 2年夏季频繁发生的地震和小震震群活动是由火山深部活动诱发的局部断裂活动引起.

2003年云南大姚6.2、6.1级地震序列特征分析及地震触发研究

本文采用双差定位法对2003年7月21日、10月16日云南大姚先后发生的6.2、6.1级地震及其余震序列进行精定位。结果表明,两个主震的震中位置相当接近,余震序列的空间分布呈明显的线性分布,地震序列精定位后的结果同震源机制解吻合很好,两个地震的发震断层均是近乎直立的右旋走滑断层。此次大姚6.2、6.1级双震,和云南地区大多数其它双震有所不同,余震分布并不呈现共轭分布,而近乎一条直线,两者间有部分重叠,表明两者受控于同一发震断层。相对主震而言,余震都呈不均匀分布,近乎一种单侧分布,6.2级地震的余震集中于主震的西北方向,6.1级地震的余震集中于主震的东南方向,并且6.1级地震是6.2级地震在同一断层向东南端延伸的另一次破裂。库仑破裂静应力变化Δσf研究结果表明,7月21日6.2级地震对10月16日6.1级地震有明显的触发作用,两个主震对断层外余震的发生均有不同程度的应力触发作用,并且2000年姚安6.5级地震对大姚两次地震的发生也有触发作用。

基于背景应力场与微震活动性的注浆帷幕突水危险性评价

为了研究背景应力场、微震活动规律和突水危险性之间的关系,结合张马屯铁矿注浆帷幕共同体堵水工程,运用已经建立并运行的ESG微震监测系统,圈定微破裂形成并积聚的三维空间,划分注浆帷幕共同体的突水危险区域。通过三维有限元程序MSC.PATRAN建立矿帷幕共同体的三维力学模型,模拟高水压下的背景应力场分布,得到矿帷幕共同体的应力场集中区域。二者对比结果表明:帷幕西南区域和矿体采空区两侧积聚了大量的微震定位事件,微震活动性信息较为明显;而在上述2个区域,高水压力和开采扰动使原应力场发生极大改变,出现了明显的地应力集中现象,说明应力场的扰动会诱发微破裂的萌生、发展和贯通。微震活动规律与背景应力场表现出了很好的一致性,采用不同的科研手段分析和预测注浆帷幕共同体背景应力场和微震活动规律的前兆性信息特征,并且初步评价其突水危险性。研究成果可以指导工程技术人员采取相应的开采方式和防治措施,为井下开采活动的正常运行提供安全保障。

复杂电能质量扰动事件源定位方法

复杂电能质量扰动事件包含多个相关的基本事件和多个扰动事件源。在对复杂扰动事件的类型和时空特征进行分析的基础上,提出一种复杂电能质量扰动事件源定位方法。采用原子算法检测扰动事件,给出根据各基本事件的起止时间进行扰动区段划分的方法;采用叠加原理对瞬时功率进行分析,提出根据扰动能量的极性对各区段扰动事件源进行定位。算例结果表明,该方法能够实现复杂电能质量扰动事件源定位。

铁路应急服务设施双阶段组合选址模型研究

在对具有区间性质的铁路应急需求点分析的基础上,针对铁路应急服务设施备选点未知且需建数目给定的选址问题,对传统单阶段选址模型进行改进,提出了综合考虑应急服务公平性及响应时效性的双阶段组合选址模型,并结合实例,验证了模型及算法的有效性.针对备选点未知且需建数目给定情况下的铁路应急服务设施双阶段组合选址问题所得的选址方案,应急服务半径降低了21.7%,应急服务水平差异性减少了35.8%,提高了整个系统的应急服务水平.本文提出的双阶段组合选址模型既适用于局部范围的应急服务设施选址也适用于全国范围的铁路应急服务设施选址,适用于备选点未知且给定建设数目的应急设施选址也适用于存在多个备选方案多目标布局优化的应急设施选址问题.