Automatically positioning microseismic sources in mining by the stereo tomographic method using full wavefields

For microseisimic monitoring it is difficult to determine wave modes and their propagation velocity. In this paper, we propose a new method for automatically inverting in real time the source characteristics of microseismic events in mine engineering without wave mode identification and velocities. Based on the wave equation in a spherical coordinate system, we derive a tomographic imaging equation and formulate a scanning parameter selection criterion by which the microseisimic event maximum energy and corresponding parameters can be determined. By determining the maximum energy positions inside a given risk district, we can indentify microseismic events inside or outside the risk districts. The synthetic and field examples demonstrate that the proposed tomographic imaging method can automatically position microseismic events by only knowing the risk district dimensions and range of velocities without identifying the wavefield modes and accurate velocities. Therefore, the new method utilizes the full wavefields to automatically monitor microseismic events.

Temporal and Spatial Distribution of DIN and DIP Concentrations and Source Apportionment Along the Bohai Sea of China During 2015-2022

The Bohai Sea is one of the most polluted sea areas in China.In this study,we used 2184 integrated concentrations of dissolved inorganic nitrogen(DIN)and dissolved inorganic phosphorus(DIP)in the Bohai Sea of China during spring(March,April,and May),summer(June,July,and August),and autumn(October and November)from 2015 to 2022 to explore the trends and sources of nutrients variations.From 2015 to 2022,DIN showed a downward trend until 2020 and then an upward trend,whereas DIP exhibited a stable trend with a slight decrease.The concentrations of DIN and DIP had similar seasonal pattern which was the highest in autumn(0.292±0.247 mg/L for DIN and 0.013±0.016 mg/L for DIP)but lower in spring(0.267±0.238 mg/L for DIN and 0.006±0.010 mg/L for DIP)and summer(0.263±0.324 mg/L for DIN and 0.008±0.010 mg/L for DIP).Sources of DIN and DIP apportioned by the positive matrix factorization(PMF)model were riverine input,sediment resuspension,sewage discharge,atmospheric deposition,and underground input.During 2015-2022,the largest contributor to DIN was sewage discharge(28.7%)and the largest contributor to DIP was sediment resuspension(44.6%).Seasonally,DIN in spring and autumn was dominated by sewage discharge(45.4%and 27.8%,re-spectively).Whereas in summer,it was dominated by riverine input(32.4%)and atmospheric deposition(29.7%).DIP was dominated by sediment resuspension during all three seasons(35.8%-52.5%).In addition,the increase in DIN concentrations in 2021 and 2022 were mainly due to the incremental input of river discharge and atmospheric deposition caused by increased precipitation during sum-mer and autumn.

Technique of Position Sensitive Detector with Alternating Light Source

The signal processing circuits of position sensitive detector(PSD) with alternating light source are presented.The measuring device of PSD with alternating light source can effectively eliminate the interference made by light noise signal.

A study on the characterization of smoke movement in shafts with different fire source positions

In this study,experimental and numerical simulation methods were combined to simulate the changing course of the temperature and velocity fields in nine different fire scenes. The characteristics of smoke movement in shafts with different fire source position factors(h/H) were quantitatively investigated,and the non-dimensional fitting function between the fire source position factors and the maximum temperature was deduced. The results showed that the location of the neutral plane moved upward as the fire source rose,and all the generated smoke spread to the upper areas;however,there was barely any smoke in the lower areas. The maximum temperature was inversely proportional to the fire source position factor;the higher the source position is,i.e. the higher the ratio factor is,the lower the maximum temperature is in the shaft. The experimental verification of the fire dynamics simulator(FDS) showed good results.

Effects of sonic speed on location accuracy of acoustic emission source in rocks

To quantitatively study the location errors induced by deviation of sonic speed, the line and plane location tests were carried out. A broken pencil was simulated as acoustic emission source in the rocks. The line and plane location tests were carried out in the granite rod using two sensors and the cube of marble using four sensors, respectively. To compare the position accuracy between line and plane positions, the line poison test was also carried out on the marble surface. The results show that for line positioning, the maximum error of absolute distance is about 0.8 cm. With the speed difference of 200 m/s, the average value of absolute difference from the position error is about 0.4 cm. For the plane positioning, in the case of the sensor array of 30 cm, the absolute positioning distance is up to 8.7 cm. It can be seen that the sonic speed seriously impacts on the plane positioning accuracy. The plane positioning error is lager than the line positioning error, which means that when the line position can satisfy the need in practical engineering, it is better to use the line position instead of the plane location. The plane positioning error with the diagonal speed is the minimum one.

Characterization and Source Apportionment of Volatile Organic Compounds in Urban and Suburban Tianjin, China

Tianjin is the third largest megacity and the fastest growth area in China,and consequently faces the problems of surface ozone and haze episodes.This study measures and characterizes volatile organic compounds （VOCs）,which are ozone precursors,to identify their possible sources and evaluate their contribution to ozone formation in urban and suburban Tianjin,China during the HaChi （Haze in China） summer campaign in 2009.A total of 107 species of ambient VOCs were detected,and the average concentrations of VOCs at urban and suburban sites were 92 and 174 ppbv,respectively.Of those,51 species of VOCs were extracted to analyze the possible VOC sources using positive matrix factorization.The identified sources of VOCs were significantly related to vehicular activities,which specifically contributed 60％ to urban and 42％ to suburban VOCs loadings in Tianjin.Industrial emission was the second most prominent source of ambient VOCs in both urban and suburban areas,although the contribution of industry in the suburban area （36％） was much higher than that at the urban area （16％）.We conclude that controlling vehicle emissions should be a top priority for VOC reduction,and that fast industrialization and urbanization causes air pollution to be more complex due to the combined emission of VOCs from industry and daily life,especially in suburban areas.

Linear Track Estimation Using Double Pulse Sources for Near-Field Underwater Moving Target

The double pulse sources （DPS） method is presented for linear track estimation in this work. In the field of noise identification of underwater moving target, the Doppler will distort the frequency and amplitude of the radiated noise. To eliminate this, the track estimation is necessary. In the DPS method, we first estimate bearings of two sinusoidal pulse sources installed in the moving target through baseline positioning method. Meanwhile, the emitted and recorded time of each pulse are also acquired. Then the linear track parameters will be achieved based on the geometry pattern with the help of double sources spacing. The simulated results confirm that the DPS improves the performance of the previous double source spacing method. The simulated experiments were carried out using a moving battery car to further evaluate its performance. When the target is 40-60m away, the experiment results show that biases of track azimuth and abeam distance of DPS are under 0.6° and 3.4m, respectively. And the average deviation of estimated velocity is around 0.25m/s.

Performance of a New Ion Source for KSTAR Tokamak Plasma Heating

In the experimental campaign of 2010 and 2011 on KSTAR, the NBI-1 system was equipped with one prototype ion source and operated successfully, providing a neutral beam power of 0.7-1.6 MW to the tokamak plasma. The new ion source planned for the 2012 KSTAR campaign had a much more advanced performance compared with the previous one. The target performance of the new ion source was to provide a neutral deuterium beam of 2 MW to the tokamak plasma. The ion source was newly designed, fabricated, and assembled in 2011. The new ion source was then conditioned up to 64 A/100 keV over a 2-hour beam extraction and performance tested at the NB test stand （NBTS） at the Korea Atomic Energy Research Institute （KAERI） in 2012. The measured optimum perveance at which the beam divergence is a minimum was about 2.5μP, and the minimum beam divergent angle was under 1.0° at 60 keV. These results indicate that the 2.0 MW neutral beam power at 100 keV required for the heating of plasma in KSTAR can be delivered by the installation of the new ion source in the KSTAR NBI-1 system.

Shallow water source localization using a mobile short horizontal array

This paper presents an approach to the challenging is- sue of passive source localization in shallow water using a mobile short horizontal linear array with length less than ten meters. The short array can be conveniently placed on autonomous underwa- ter vehicles and deployed for adaptive spatial sampling. However, the use of such small aperture passive sonar systems makes it difficult to acquire sufficient spatial gain for localizing long-range sources. To meet the requirement, a localization approach that employs matched-field based techniques that enable the short ho- rizontal linear array is used to passively localize acoustic sources in shallow water. Furthermore, the broadband processing and inter-position processing provide robustness against ocean en- vironmental mismatch and enhance the stability of the estimation process. The proposed approach＇s ability to localize acoustic sources in shallow water at different signal-to-noise ratios is examined through the synthetic test cases where the sources are located at the endfire and some other bearing of the mobile short horizontal linear array. The presented results demonstrate that the positional parameters of the estimated source build up over time as the array moves at a low speed along a straight line at a constant depth.

Indoor imaging visible light positioning with sampled sparse light source and mobile device

Indoor visible light positioning becomes attractive due to the increasing demands of location-based services. This Letter proposes an indoor imaging visible light positioning scheme with a sampled sparse light source, image sensor, and gyro. An indoor positioning cellular with a single reference light source and an off-the-shelf mobile device is demonstrated. Experimental results show that the 3-dimensional positioning error is only several centimeters even with a rotated, rolled, and pitched mobile device. The proposed scheme is convenient and cost effective because the transmitter takes advantage of the existing lighting infrastructure and the receiver is a commercial mobile phone without any extra accessories.

基于中子位置灵敏探测器对点源的三维定位方法研究

使用中子法对密封容器内的放射源进行定位具有重要的现实意义。本研究使用4根矩形分布的中子位置灵敏探测器对探测空间内AmLi源进行定位,首先使用蒙特卡罗方法设计了探测器的慢化屏蔽体;然后设计了延迟电路加到探测器的一端,根据探测器两端探测到中子信号的时间差来确定源y轴(探测器轴向)的位置坐标,并对每个探测器的轴向位置函数进行了刻度;利用探测器围绕密封容器搭建测量空间,使用相邻探测器探测到中子计数率的比值来确定x轴和z轴(另两个方向)的位置坐标并进行了函数刻度。测量时,首先选择计数率最大的探测器来确定源的轴向坐标,再根据与此探测器相邻两根探测器计数率的比值来确定源的另两个方向的坐标,实现了对源的定位。使用该方法测量了点源在探测器空间内的5个不同位置,每个坐标轴上的定位偏差均在1.5 cm之内,并对造成偏差的原因进行了分析。该方法验证了使用中子位置灵敏探测器对放射源进行定位的可行性,并为进一步测量核设施工艺设备内核材料的位置打下了良好的基础。

面向无人智能小车的双验证安全定位方法

针对无人智能小车在网络、硬件、操作系统和软件方面存在众多安全隐患,易受到物理或远程安全攻击,使其偏离配送轨迹导致配送任务失败,甚至被攻击者操控干扰工厂正常运行的问题,提出了一种面向无人智能小车的双验证安全定位方法。在无人智能小车端,利用已有的Wi-Fi网络基础设施进行指纹定位,并设计特征融合策略实现Wi-Fi和磁场指纹的动态融合;在环境端,部署多个监测点采集无人智能小车发出的声音信号计算到达时间差,并根据空间分割方法计算小车位置。在此基础上,通过将无人智能小车上报的位置信息和监测点计算的位置坐标进行对比验证,一旦发现小车位置出现异常则进行异常告警,从而保证无人智能小车的正常运转工作。在真实室内场景下的实验结果表明,所提方法可以有效跟踪目标设备的位置坐标,定位精度优于现有基准算法。

基于地震信号的滚石定位及动力参数反演研究

基于滚石诱发地震信号可快速准确地获取滚石灾害信息,对灾情评估至关重要。开展了滚石冲击坡面地震动监测现场原位试验,揭示了滚石冲击地震信号时频域特征规律,分析了到时法与极化法的震源定位性能,并基于量纲分析法建立了滚石体积与冲击速度反演模型。结果表明:滚石冲击坡面(弹跳阶段)产生的地震信号表现为短持时、宽频带的三角状脉冲特征;结合到时法和极化法震源定位理论,实现了滚石冲击坡面的空间定位,得出到时法是更为优良的滚石冲击震源定位方法,其平均相对定位误差不超过10%;基于无量纲反演模型预测的滚石体积、冲击速度与实际结果吻合较好,平均预测误差均低于20%。研究成果可为滚石灾害动力学参数的快速获取提供理论与技术支持。

2021年济南市大气PM_(2.5)中PAHs污染特征及其来源解析

目的分析济南市2021年细颗粒物(fine particulate matter,PM_(2.5))中PAHs污染特征及来源分析,为济南市大气环境综合治理提供相关数据支持。方法根据济南市区域分布特点选取2个有代表性监测点,每月的10—16日进行连续监测,使用超高效液相色谱仪对16种PAHs进行检测,分析济南市PM_(2.5)中PAHs变化趋势及特征,使用特征比值和PMF模型对PM_(2.5)中PAHs进行源解析。结果PAHs以4环和6环为主,具有显著的季节性变化趋势,即冬季>秋季>春季>夏季,1月份污染情况尤为突出;秋季和冬季中7种高致癌风险PAHs所占比例高于其他季节,历城区各季节PAHs质量浓度均高于市中区;结合特征比值和PMF对PAHs来源分析,冬季主要污染源是工业和石油产品挥发源、交通源;秋季主要为燃煤燃烧源、工业和石油产品挥发源和交通源。结论济南市PM_(2.5)中PAHs存在一定的污染,需加大清洁能源的使用,同时进一步加强秋、冬季,尤其是采暖季燃煤燃烧、工业和石油产品挥发和交通等污染源的控制。

基于伪磁梯度张量混合方向tilt梯度的磁源定位方法及其应用:以内蒙古塔木素铀矿床为例

斜磁化磁源的准确定位是磁法勘探有效圈定场源分布及划分断裂构造的重要依据.但受磁化方向影响,总磁异常与地质体分布并无明显对应关系.为此,本文从总磁异常垂向积分出发,推导出了伪磁梯度张量,定义了伪磁梯度张量的混合方向tilt梯度及混合方向解析信号振幅,提出了基于伪磁梯度张量混合方向tilt梯度水平导数组合的场源定位方法.模型试验表明,相对于解析信号振幅、tilt梯度的总水平导数及方向tilt梯度的总水平导数模这3种受磁化方向影响较小的方法,本文提出的磁源定位方法能够更有效地反映出不同磁化方向的磁源位置,具有更强的识别能力和定位精度.在内蒙古塔木素铀矿床的航磁资料应用中,新方法较好地展示出了已知断裂带的展布及出露岩浆岩的分布,同时有效地提取了塔木素铀矿床上方的弱磁异常信息,处理结果为研究区圈定隐伏岩体、划分隐伏断裂及扩大铀矿找矿靶区提供了依据.

基于多源信息融合的RBF神经网络室内可见光定位算法

针对基于接收信号强度(RSS)的定位技术易受环境干扰而导致定位精度不高和稳定性较差的问题,提出了一种基于多源信息融合的径向基函数(RBF)神经网络室内可见光定位算法。通过将图像的颜色矩特征与RSS矩特征融合,构建指纹库,并采用RBF神经网络进行预测,实现了图像与RSS之间的优势互补,最后对定位算法进行了验证。实验结果表明,经过优化的多源信息融合定位算法较单一RSS定位算法的定位精度提高了9.4%。

基于扫频OCT测量的术前晶状体界面位置对于白内障术后人工晶状体真实位置的预测价值

目的 探讨基于扫频OCT(SS-OCT)技术的光学生物测量仪IOLMaster 700获得的晶状体界面位置(IIP)对白内障术后人工晶状体(IOL)的真实位置(ALP)的预测价值。方法 回顾性描述性研究。选取2021年7月至2022年7月于苏州大学附属第一医院眼科接受白内障手术的年龄相关性白内障患者208例208眼为研究对象。根据植入的IOL不同分为2组:IQ组(80眼)术中植入IQ IOL;ZCB组(128眼)术中植入ZCB IOL。使用基于SS-OCT的生物测量仪IOLMaster 700在术前和术后3个月对患眼进行生物学参数的测量,获取ALP、术后前房深度(ACD)、IOL厚度等参数,并计算IOL位置误差。结果 白内障术后,208眼的绝对屈光度预测误差(ARPE)为(0.43±0.35) D,134眼(64.4%)的ARPE<0.50 D。与IQ组相比,ZCB组患眼的ALP和ALP2值更大(均为P<0.001)。与IQ组相比,ZCB组ARPE≥0.50 D患眼的IIP显著降低(P=0.028);在ZCB组患者中,与ARPE<0.50 D相比,ARPE≥0.50 D患眼的IIP显著降低(P=0.041)。两组患者的ALP与IIP均具有较好的相关性(IQ组:r=0.815,P<0.001;ZCB组:r=0.757,P<0.001);ALP2与IIP也均具有较好的相关性(IQ组:r=0.797,P<0.001;ZCB组:r=0.743,P<0.001)。通过IIP和术前参数可以获得线性表达式来预测ALP(IQ组、ZCB组的R^(2)分别为0.70、0.68)。结论 基于SS-OCT技术的IOL Master 700测量的IIP位置与白内障术后的ALP相关,可用于优化IOL度数计算。

检察机关参与诉源治理的角色定位及实践路径

诉源治理作为社会治理理念的实践创新成果之一,注重从源头预防化解矛盾纠纷。目前,诉源治理理念的内涵逻辑基本明晰,诉源治理制度的体系框架逐步确立。同样,依法履行法律监督职能的检察机关如何参与诉源治理,则成为提升司法机关诉源治理能力以及健全诉源治理体系的新命题。检察机关作为参与社会治理的重要部门,应当从自身法定职能及要求出发,以“法律监督者”和“法治保障者”的角色定位来整合相关社会治理资源,为诉源治理体系注入法治化和规范化的力量,努力以非诉讼矛盾纠纷的预防化解和诉讼内矛盾纠纷的预防化解两条途径来构建与完善诉源治理的实践路径,从而实现检察机关参与社会治理的司法性职能和治理性职能之间的有效衔接,以推动诉源治理社会共治体系的形成。

河套灌区地表水污染溯源分析

针对河套灌区地表水污染来源不清、贡献不明的问题,本文基于9个监测断面月度水质数据,分析灌区地表水环境特征,引用正定矩阵因子分析模型解析污染来源及其空间差异性.结果表明:(1)有机污染指标(COD_(Mn)、COD、BOD_(5))和总氮是河套灌区的主要超标因子,总氮指标低于GB 3838-2002《地表水环境质量标准》Ⅲ类标准的样品数量占比超过67%,整体来说支排干水质差于总排干.其中,七排干入总排干口污染最重,COD_(Mn)与总磷浓度分别超GB 3838-2002Ⅲ类水质标准限值的109%和160%;其次是五排干入总排干口和三排干入总排干口.(2)散养畜禽粪污和秸秆还田以及生产生活污水输入分别是河套灌区地表水有机污染和氮的主要来源,贡献率分别达56.22%和47.82%.(3)河套灌区地表水污染来源具有明显的空间异质性,种植业磷肥输入是影响二排干、三排干和总排干上游水质的主要因素,生产和生活污水输入是影响五排干、七排干和总排干下游水质的主要因素.本文依托监测断面常规监测指标结合数学模型方法,实现了对河套灌区沟渠系统地表水污染的定量溯源,并分析了各监控断面的主要污染风险.

地下水污染源解析方法研究进展

地下水污染具有隐蔽性,污染过程缓慢且难以治理,近年来中国高度重视地下水环境保护工作,作为支撑“以防为主”保护理念的地下水污染源解析技术研究已成为地下水污染防治领域的研究热点。介绍了国内外地下水污染源解析方面的主要技术方法,包括同位素法、荧光光谱法、地质统计学法、主成分分析法、正定矩阵因子分析模型、自组织映射技术6种常用方法的基本原理及在地下水污染识别领域的应用和研究动态,总结了这些方法的优缺点与适用性,并就上述方法在地下水污染研究中的应用前景和发展趋势进行了展望。