Localization for mixed near-field and far-field sources under impulsive noise

In order to solve the problem that the performance of traditional localization methods for mixed near-field sources(NFSs)and far-field sources(FFSs)degrades under impulsive noise,a robust and novel localization method is proposed.After eliminating the impacts of impulsive noise by the weighted out-lier filter,the direction of arrivals(DOAs)of FFSs can be estimated by multiple signal classification(MUSIC)spectral peaks search.Based on the DOAs information of FFSs,the separation of mixed sources can be performed.Finally,the estimation of localizing parameters of NFSs can avoid two-dimension spectral peaks search by decomposing steering vectors.The Cramer-Rao bounds(CRB)for the unbiased estimations of DOA and range under impulsive noise have been drawn.Simulation experiments verify that the proposed method has advantages in probability of successful estimation(PSE)and root mean square error(RMSE)compared with existing localization methods.It can be concluded that the proposed method is effective and reliable in the environment with low generalized signal to noise ratio(GSNR),few snapshots,and strong impulse.

NEAR-FIELD SOURCE LOCALIZATION METHOD AND APPLICATION USING THE TIME REVERSAL MIRROR TECHNIQUE

In order to develop the acoustic keyboard for Personal Computer(PC),it is necessary to seek high-precision near-field source localization algorithm for identifying the keyboard characters.First of all,the focusing property of Time Reversal Mirror(TRM) is introduced,and then a mathe-matical model of microphone array receiving typing sound is established according to the realization of acoustic keyboard from which the TRM localization algorithm is carried out.The results through computer simulation show that the localization Root Mean Square Error(RMSE) performance of the algorithm can reach 10-3,which demonstrates that the algorithm possesses a high accuracy for the actual near-field acoustic source localization,with potential of developing the computer acoustic keyboard.Furthermore,for the purpose of testing its effect on actual near-field source localization,we organize three experiments for acoustic keyboard characters localization.The experiment results show that the positioning error of TRM algorithm is less than 1 cm within a provided acoustic keyboard region.This will provide theoretical guidance for the further research of computer acoustic keyboard.

A search-free near-field source localization method with exact signal model

Most of the near-field source localization methods are developed with the approximated signal model,because the phases of the received near-field signal are highly non-linear.Nevertheless,the approximated signal model based methods suffer from model mismatch and performance degradation while the exact signal model based estimation methods usually involve parameter searching or multiple decomposition procedures.In this paper,a search-free near-field source localization method is proposed with the exact signal model.Firstly,the approximative estimates of the direction of arrival(DOA)and range are obtained by using the approximated signal model based method through parameter separation and polynomial rooting operations.Then,the approximative estimates are corrected with the exact signal model according to the exact expressions of phase difference in near-field observations.The proposed method avoids spectral searching and parameter pairing and has enhanced estimation performance.Numerical simulations are provided to demonstrate the effectiveness of the proposed method.

Hybrid Slip Model for Near-Field Ground Motion Estimation Based on Uncertainty of Source Parameters

The hybrid slip model used to generate a finite fault model for near-field ground motion estimation and seismic hazard assessment was improved to express the uncertainty of the source form of a future earthquake.In this process, source parameters were treated as normal random variables, and the Fortran code of hybrid slip model was modified by adding a random number generator so that the code could generate many finite fault models with different dimensions and slip distributions for a given magnitude.Furth...

A Blasting Sources-Based Approach to Inspection of Faults in Dam

An approach to inspection of incipient faults in dams by non-destructive testing is a so far emerging inspection technology in the world.In this paper,inspection principles,system integrity and key items for the new blasting source-based technology for inspection of incipient faults in dams,different from common non-destructive testing,are presented,following briefing experiences in dam inspection by elastic wave CT in recent years.Specific procedures and goals for further spreading and application as well as conclusion are introduced finally.

Decomposition of the Unsteady Wave Patterns for Bessho form Translating-Pulsating Source Green Function

In order to interpret the physical feature of Bessho form translating-pulsating source Green function, the phase function is extracted from the integral representation and stationary-phase analysis is carried out in this paper. The complex characteristics of the integral variable and segmentation of the integral intervals are discussed in m complex plane. In θ space, the interval [-π/2+φ,-π/2+φ-iε] is dominant in the near-field flow, and there is a one-to-one correspondence between the real intervals in m space and the unsteady wave patterns in far field. If 4τ>1(τ is the Brard number), there are three kinds of propagation wave patterns such as ring-fan wave pattern, fan wave pattern and inner V wave pattern, and if 0<4τ<1, a ring wave pattern, an outer V and inner V wave pattern are presented in far field. The ring-fan or ring wave pattern corresponds to the interval [-π+α,-π/2+φ] for integral terms about k2, and the fan or outer V wave pattern and inner V wave pattern correspond to [-π+α,-π/2) and(-π/2,-π/2+φ] respectively for terms about k1. Numerical result shows that it is beneficial to decompose the unsteady wave patterns under the condition of τ≠0 by converting the integral variable θ to m. In addition, the constant-phase curve equations are derived when the source is performing only pulsating or translating.

钻爆法机械化施工隧道随钻地震波超前地质探测技术研究

为适应我国隧道建设机械化、智能化、无人化发展趋势,围绕钻爆法机械化施工隧道,提出以凿岩台车破岩振动为震源的钻爆法机械化施工隧道随钻地震波超前地质探测技术。针对凿岩台车多震源连续激发带来的地震数据波场混叠、有效信息难以识别问题开展相关研究,提出VMD-SVD-RobustICA三臂混合先导信号分离方法与脉冲反褶积-小波域互相关地震记录重构方法,可实现三臂混合先导信号的分离与有效反射信号的提取。工程实践证明,利用凿岩台车搭载式无线高精度探测装备,该技术可初步实现“边钻边探”,降低预报环节对钻爆法机械化施工隧道正常施工带来的影响。最后,明确该技术目前存在的问题及解决思路。

高炉原料硫含量与煤气硫含量相关性分析

对某钢铁高炉原料中的焦炭、喷吹煤、烧结矿硫含量进行了统计分析,同时分析了对应区间高炉煤气硫化氢、羰基硫含量,利用统计分析软件分析了高炉各原料中硫含量与高炉煤气中硫化氢、羰基硫的相关性,提出了要降低高炉煤气硫含量,需要适当降低焦炭、烧结矿的硫含量,适当提高喷吹煤中硫含量。分析的结果对支撑高炉煤气硫含量源头减排提供了数据支撑。

安钢高炉煤气精脱硫技术工业实践

结合当前环保形势和政策背景,分析了高炉煤气的典型特点和主流工艺路线,提出预处理水解和兰炭吸附的工艺组合,阐述了该工艺的技术原理和工业实践情况,该技术的应用和推广将带来广泛的环境效益和经济社会效益。

基于能量守恒的气枪主动震源激发实验震级计算

分别运用Baker公式、Kinney公式、Broad公式计算甘肃刘家峡气枪主动源一次常规实验激发所释放的能量,并利用能量与震级之间的经验公式,估算一次常规实验产生地震的震级。通过分析刘家峡主动源实验场附近固定数字测震台站记录的单次激发数据发现,气枪激发时所释放的能量并未完全转换为地震波,如气枪主气室在爆破瞬间并非完全绝热,有部分能量随着热量传递而散失,故通过能量守恒方法计算的震级略大。实验结论与Kinney公式计算结果的一致性较好,符合实验实际工况条件。

岩塞爆破在水源地取水口工程中的应用研究

以兰州水源地建设工程取水口岩塞爆破为例,分析了岩塞爆破的特点和基本设计要求,探讨了岩塞形状和尺寸的确定、聚渣坑设计、爆破孔布置、装药结构、起爆网路、施工流程等岩塞爆破实施的主要技术措施和注意事项。通过振动监测对爆破实施效果进行分析,结果证明该爆破方案合理可行。

Evaluation of effectiveness of polymer coatings in reducing blastinduced deformation of steel plates

Incorporating elastomers such as polymers in protective structures to withstand high energetic dynamic loads,has gained significant interest.The main objective of this study is to investigate the influence of a Polyurea coating towards the blast-induced response in steel plates.As such,Polyurea coated steel plates were tested under near-field blast loads,produced by the detonation of 1 kg of spherical nitromethane charges,at a standoff distance of 150 mm.Mild steel(XLERPLATE 350)and high-strength steel(BIS80)plates with thicknesses of 10 mm were Polyurea coated with thicknesses of 6 mm and 12 mm on either the front(facing the charge)or the back face.The deformation profiles were measured using 3D scanning.Numerical simulations were performed using the non-linear finite element code LS-DYNA.The strain-dependent behaviour of the steel and Polyurea were represented by Johnson-cook and Money-Rivlin constitutive models,respectively.The numerical models were validated by comparing the plate deflection results obtained from the experiments and were then used in the subsequent parametric study to investigate the optimum thickness of the Polyurea coating.The results indicate that back face coating contributes towards an approximately 20%reduction in the residual deformation as well as the absence of melting of the Polyurea layer,while the front-face coating can be used a means of providing additional standoff distance to the steel plates.

Prediction of near-field strong ground motions for scenario earthquakes on active fault

A method to predict near-field strong ground motions for scenario earthquakes on active faults is proposed. First, macro-source parameters characterizing the entire source area, i.e., global source parameters, including fault length, fault width, rupture area, average slip on the fault plane, etc., are estimated by seismogeology survey, seismicity and seismic scaling laws. Second, slip distributions characterizing heterogeneity or roughness on the fault plane, i.e., local source parameters, are reproduced/evaluated by the hybrid slip model. Finally, the finite fault source model, developed from both the global and local source parameters, is combined with the stochastically synthetic technique of ground motion using the dynamic comer frequency based on seismology. The proposed method is applied to simulate the acceleration time histories on three base-rock stations during the 1994 Northridge earthquake. Comparisons between the predicted and recorded acceleration time histories show that the method is feasible and practicable.

基于微震监测的钻爆法施工隧道围岩稳定性综合判断方法研究

为了对深埋钻爆法施工隧道围岩稳定状态或灾害进行综合解译与判断。首先,基于震源参数空间提出了微震事件分类和围岩损伤等级划分方法;其次,构建了多微震参数的时间序列,对比揭示了爆破施工期间围岩稳定、塌方和岩爆3种状态的微震特征;最终,提出了钻爆法施工深埋隧道围岩稳定性的综合判断方法。这套方法适用于深埋隧道爆破施工期间围岩稳定状态、塌方和岩爆灾害的判断,并在此基础上结合地质条件对灾害风险等级进行判定。研究结果表明:钻爆法施工期间围岩稳定、塌方和岩爆3种状态在震源参数空间和微震时间序列趋势中均有独特的特征及规律;围岩稳定阶段仅在爆破后短时间内出现强烈的应力调整;围岩稳定性异常阶段在爆破后微震事件长时间持续活跃且累积能量、累积事件数、累积视体积曲线快速增长,能量指数曲线快速下降。研究结果可为钻爆法施工深埋隧道围岩稳定性判断、灾害预警及防控方案提供重要参考,也可为其他相似的工程提供借鉴。

隧道爆破振动信号时频谱增强优化分析

针对隧道爆破振动信号时频解析度不足的难题,运用基于卷积神经网络的时频图像增强算法,增强实测隧道爆破信号时频图像,捕获到爆破信号能量在时频域上的聚集范围,从而重构得到反映爆破特征的真实信号;根据真实信号对爆破网络中雷管的起爆时刻进行了精确判别,识别隧道爆破雷管灾害源特征。分析表明:基于卷积神经网络的时频图像增强算法可有效抑制信号中的交叉项,最大限度地保留信号自有项,提高爆破信号能量聚集性和时频解析度;不同批次雷管混用是隧道安全的主要致灾因素,应加强监管以实现隧道安全高效施工。

钢铁企业高炉煤气柜重大危险源评估应用

对高炉煤气柜重大危险源评估做简要阐述,着重对高炉煤气柜的HAZOP分析过程进行了论述。从安全角度阐述了HAZOP分析运用对钢铁企业煤气柜安全的重要性,介绍了钢铁企业煤气柜的选型以及高炉煤气柜的工艺安全技术优化路线等,最终形成技术可行、经济实用的工程方案,并运用于示范工程中。

独头隧道爆破冲击波传播特征与爆源因素影响分析

为评估在隧道爆破冲击波作用下人员安全和建筑物毁伤问题,需要明晰施工隧道与交通隧道内爆破空气冲击波传播特征的区别。利用ANSYS/LS-DYNA软件对比分析独头与双向开口隧道内冲击波传播过程的差异性,研究爆源等效炸药当量、炸药多孔起爆及爆源位置等因素对爆破冲击波传播影响机制。结果表明:独头隧道内爆破冲击波传播经历三维球面波逐渐转换至一维平面波的3阶段变化模式,且独头隧道端部边界约束初始球面波几何扩散,经壁面反射叠加的超压增幅达20%;爆源炸药当量影响着波阵面变化,3阶段变化模式的波阵面转换位置与炸药当量呈幂函数负相关关系,随炸药当量提高而在更接近爆源位置转换;多炮孔起爆工况近场超压更大,而进入远场一维平面波传播区域,多炮孔起爆和爆源位置对冲击波超压分布特征影响有限;与单个爆源中心起爆工况相比,超压相对误差小于5%。

Source model for blasting vibration

By analyzing and comparing the experimental data, the point source moment theory and the cavity theory, it is concluded that the vibrating signals away from the blasting explosive come mainly from the natural vibrations of the geological structures near the broken blasting area. The source impulses are not spread mainly by the inelastic properties (such as through media damping, as believed to be the case by many researchers) of the medium in the propagation pass, but by this structure. Then an equivalent source model for the blasting vibrations of a fragmenting blasting is proposed, which shows the important role of the impulse of the source's time function under certain conditions. For the purpose of numerical simulation, the model is realized in FEM, The finite element results are in good agreement with the experimental data.

Underwater moving noise source identification based on hybrid near-field acoustical holography

Near-field acoustical holography (NAH) is a powerful tool for identifying noise sources and visualizing acoustic field. By recording the acoustic pressures in the near-field, the acoustic quantities in the whole 3-D field can be reconstructed and predicted. However, the current theory of NAH is not applicable to tracking large scale moving noise sources. Therefore, the hybrid near-field acoustical holography is developed for reconstructing acoustic radiation, which is derived from statistically optimized near-field acoustical holography (SONAH) and moving frame acoustical holography (MFAH). The theoretical formulation is systematically addressed. This method enables us to visualize the noise generated by moving noise sources and the measurement array can be smaller than the source, which improves the practicability and efficiency of this technology. Numerical simulations are presented to demonstrate the advantages of hybrid NAH. Then, two experiments have been carried out with a line array of hydrophones. The results of simulations and experiments support the proposed theory, which shows the advantage of hybrid NAH in the reconstruction of an acoustic field in an underwater holographic measurement.

Passive localization of 3-D near-field sources in coexisted multiplicative noise and additive noise

By exploiting thvorable characteristics of a uniIbrm cross-array, a passive localization algorithm of narrowband sources in the spherical coordinates （azimuth, elevation and range） is proposed. Based on the properly chosen sensor outputs, we compute the third-order cyclic moment matrices, and exploit a pre-calibration technique to eliminate multiplicative noise. Then, we construct a parallel factor （PARAFAC） model, and adopt trilinear altemating least squares regression （TALS） to estimate three-dimensional （3-D） near-field parameters. The investigated algorithm is efficient in the sense that it can eliminate multiplicative noise and additive noise, provide the improved estimation accuracy, as well as avoid the parameter-pairing procedure. Simulation results are carried out to demonstrate the performance of the proposed algorithm.