Kinematic deformation and intensity assessment of the 2021 Maduo M_(S)7.4 earthquake in Qinghai revealed by high-frequency GNSS

Rapid acquisition of the kinematic deformation field and seismic intensity distribution of large earthquakes is crucial for postseismic emergency rescue,disaster assessment,and future seismic risk research.The advancement of GNSS observation and data processing makes it play an important role in this field,especially the high-frequency GNSS.We used the differential positioning method to calculate the 1 HZ GNSS data from 98 sites within 1000 km of the M_(S)7.4 Maduo earthquake epicenter.The kinematic deformation field and the distribution of the seismic intensity by using the peak ground velocity derived from displacement waveforms were obtained.The results show that:1)Horizontal coseismic response deformation levels ranging from 25 mm to 301 mm can be observed within a 1000 km radius from the epicenter.Coseismic response deformation on the east and west sides shows bilateral asymmetry,which markedly differs from the symmetry presented by surface rupture.2)The seismic intensity obtained through high-frequency GNSS and field investigations exhibits good consistency of the scope and orientation in the high seismic intensity area,although the former is generally slightly smaller than the latter.3)There may exist obstacles on the eastern side of the seismogenic fault.The Maduo earthquake induced a certain tectonic stress loading effect on the western Kunlun Pass-Jiangcuo fault(KPJF)and Maqin-Maqu segment,resulting in higher seismic risk in the future.

Dynamic Response of Foundations during Startup of High-Frequency Tunnel Equipment

The specialized equipment utilized in long-line tunnel engineering is evolving towards large-scale,multifunctional,and complex orientations.The vibration caused by the high-frequency units during regular operation is supported by the foundation of the units,and the magnitude of vibration and the operating frequency fluctuate in different engineering contexts,leading to variations in the dynamic response of the foundation.The high-frequency units yield significantly diverse outcomes under different startup conditions and times,resulting in failure to meet operational requirements,influencing the normal function of the tunnel,and causing harm to the foundation structure,personnel,and property in severe cases.This article formulates a finite element numerical computation model for solid elements using three-dimensional elastic body theory and integrates field measurements to substantiate and ascertain the crucial parameter configurations of the finite element model.By proposing a comprehensive startup timing function for high-frequency dynamic machines under different startup conditions,simulating the frequency andmagnitude variations during the startup process,and suggesting functions for changes in frequency and magnitude,a simulated startup schedule function for high-frequency machines is created through coupling.Taking into account the selection of the transient dynamic analysis step length,the dynamic response results for the lower dynamic foundation during its fundamental frequency crossing process are obtained.The validation checks if the structural magnitude surpasses the safety threshold during the critical phase of unit startup traversing the structural resonance region.The design recommendations for high-frequency units’dynamic foundations are provided,taking into account the startup process of the machine and ensuring the safe operation of the tunnel.

Review of the Analysis and Suppression for High-frequency Oscillations of the Grid-connected Wind Power Generation System

High-frequency oscillation(HFO)of gridconnected wind power generation systems(WPGS)is one of the most critical issues in recent years that threaten the safe access of WPGS to the grid.Ensuring the WPGS can damp HFO is becoming more and more vital for the development of wind power.The HFO phenomenon of wind turbines under different scenarios usually has different mechanisms.Hence,engineers need to acquire the working mechanisms of the different HFO damping technologies and select the appropriate one to ensure the effective implementation of oscillation damping in practical engineering.This paper introduces the general assumptions of WPGS when analyzing HFO,systematically summarizes the reasons for the occurrence of HFO in different scenarios,deeply analyses the key points and difficulties of HFO damping under different scenarios,and then compares the technical performances of various types of HFO suppression methods to provide adequate references for engineers in the application of technology.Finally,this paper discusses possible future research difficulties in the problem of HFO,as well as the possible future trends in the demand for HFO damping.

Efficient activation of the Co/SBA-15catalyst by high-frequency AC-DBD plasma thermal effects for toluene removal

Dielectric barrier discharge(DBD)plasma excited by a high-frequency alternating-current(AC)power supply is widely employed for the degradation of volatile organic compounds(VOCs).However,the thermal effect generated during the discharge process leads to energy waste and low energy utilization efficiency.In this work,an innovative DBD thermally-conducted catalysis(DBD-TCC)system,integrating high-frequency AC-DBD plasma and its generated thermal effects to activate the Co/SBA-15 catalyst,was employed for toluene removal.Specifically,Co/SBA-15 catalysts are closely positioned to the ground electrode of the plasma zone and can be heated and activated by the thermal effect when the voltage exceeds 10 k V.At12.4 k V,the temperature in the catalyst zone reached 261℃ in the DBD-TCC system,resulting in an increase in toluene degradation efficiency of 17%,CO_(2)selectivity of 21.2%,and energy efficiency of 27%,respectively,compared to the DBD system alone.In contrast,the DBD thermally-unconducted catalysis(DBD-TUC)system fails to enhance toluene degradation due to insufficient heat absorption and catalytic activation,highlighting the crucial role of AC-DBD generated heat in the activation of the catalyst.Furthermore,the degradation pathway and mechanism of toluene in the DBD-TCC system were hypothesized.This work is expected to provide an energy-efficient approach for high-frequency AC-DBD plasma removal of VOCs.

Effects of unilateral superimposed high-frequency jet ventilation on porcine hemodynamics and gas exchange during one-lung flooding

BACKGROUND Superimposed high-frequency jet ventilation(SHFJV)is suitable for respiratory motion reduction and essential for effective lung tumor ablation.Fluid filling of the target lung wing one-lung flooding(OLF)is necessary for therapeutic ultrasound applications.However,whether unilateral SHFJV allows adequate hemodynamics and gas exchange is unclear.AIM To compared SHFJV with pressure-controlled ventilation(PCV)during OLF by assessing hemodynamics and gas exchange in different animal positions.METHODS SHFJV or PCV was used alternatingly to ventilate the non-flooded lungs of the 12 anesthetized pigs during OLF.The animal positions were changed from left lateral position to supine position(SP)to right lateral position(RLP)every 30 min.In each position,ventilation was maintained for 15 min in both modalities.Hemodynamic variables and arterial blood gas levels were repeatedly measured.RESULTS Unilateral SHFJV led to lower carbon dioxide removal than PCV without abnormally elevated carbon dioxide levels.SHFJV slightly decreased oxygenation in SP and RLP compared with PCV;the lowest values of PaO_(2) and PaO_(2)/FiO_(2) ratio were found in SP[13.0;interquartile range(IQR):12.6-5.6 and 32.5(IQR:31.5-38.9)kPa].Conversely,during SHFJV,the shunt fraction was higher in all animal positions(highest in the RLP:0.30).CONCLUSION In porcine model,unilateral SHFJV may provide adequate ventilation in different animal positions during OLF.Lower oxygenation and CO_(2) removal rates compared to PCV did not lead to hypoxia or hypercapnia.SHFJV can be safely used for lung tumor ablation to minimize ventilation-induced lung motion.

Therapeutic efficacy of methylprednisolone sodium succinate via diverse administration routes for mid-to high-frequency sudden sensorineural hearing loss

BACKGROUND Sudden sensorineural hearing loss(SSNHL),characterized by a rapid and unexplained loss of hearing,particularly at moderate to high frequencies,presents a significant clinical challenge.The therapeutic use of methylprednisolone sodium succinate(MPSS)via different administration routes,in combination with conventional medications,remains a topic of interest.AIM To compare the therapeutic efficacy of MPSS administered via different routes in combination with conventional drugs for the treatment of mid-to high-frequency SSNHL.METHODS The medical records of 109 patients with mid-to high-frequency SSNHL were analyzed.The patients were divided into three groups based on the route of administration:Group A[intratympanic(IT)injection of MPSS combined with mecobalamin and Ginkgo biloba leaf extract injection],Group B(intravenous injection of MPSS combined with mecobalamin and Ginkgo biloba leaf extract injection),and Group C(single IT injection of MPSS).The intervention effects were compared and analyzed.RESULTS The posttreatment auditory thresholds in Group A(21.23±3.34)were significantly lower than those in Groups B(28.52±3.36)and C(30.23±4.21;P<0.05).Group A also exhibited a significantly greater speech recognition rate(92.23±5.34)than Groups B and C.The disappearance time of tinnitus,time to hearing recovery,and disappearance time of vertigo in Group A were significantly shorter than those in Groups B and C(P<0.05).The total effective rate in Group A(97.56%)was significantly greater than that in Groups B and C(77.14%and 78.79%,χ^(2)=7.898,P=0.019).Moreover,the incidence of adverse reactions in Groups A and C was significantly lower than that in Group B(4.88%,3.03%vs 2.57%,χ^(2)=11.443,P=0.003),and the recurrence rate in Group A was significantly lower than that in Groups B and C(2.44%vs 20.00%vs 21.21%,χ^(2)=7.120,P=0.028).CONCLUSION IT injection of MPSS combined with conventional treatment demonstrates superior efficacy and safety compared to systemic administration via intravenous infusion and a single IT injection of MPSS.This approach effectively improves patients'hearing and reduces the risk of disease recurrence.

一种大尺度区域GNSS坐标时间序列自适应时空滤波方法

提出一种GNSS坐标时间序列自适应时空滤波方法,在规定阈值下将滤波区域自适应分为若干个子区域,进行共模误差的提取和去除。对陆态网184个GNSS站点垂向坐标序列进行时空滤波,3组随机实验中,自适应PCA时空滤波后的站点序列平均RMS值减少约39.7%、38.4%和39.7%,且优于整体PCA滤波。进一步分析滤波前后站点噪声特性变化,结果显示,相比于整体PCA滤波,自适应滤波方法中站点残差序列幂律噪声减少约17.8%。

GNSS约束的2022年泸定M6.8地震滑动分布及同震应力变化

2022年9月5日四川泸定县发生M6.8级强震,震中位于鲜水河断裂东南末端,野外地质调查初步结果显示本次地震并未发现明显的地表破裂迹象.本文基于震后科考GNSS流动观测和震中周边连续站观测资料,解算并提取震中90 km范围内31个测站的静态水平向同震位移.结果显示:GNSS同震形变场空间分布呈现明显的左旋走滑特征,观测到的最大水平向同震位移达23 cm,震中距50 km范围内同震位移量普遍大于1 cm.基于GNSS观测资料反演得到的同震滑动分布显示泸定地震地表破裂主要集中在磨西至田湾之间,主破裂深度2~8 km,最大滑动量~1.96 m,地震矩9.25×10^(18)N·m,对应矩震级M_W6.6.静态库仑应力结果显示本次地震增强了震源破裂区周边活动断层的库仑应力,并触发了大量余震,余震主要发生在库仑应力增强区域.结合震间闭锁分布、历史地震及库仑应力变化,我们认为未来需要密切关注与磨西断裂交接的安宁河、大凉山断裂以及康定—磨西段的地震危险性.

GNSS拟合高程代替水准测量的可行性分析:以黄河上游水电基地区域为例

GNSS拟合高程代替水准测量有重要的现实意义,有必要对其进行可行性分析。黄河上游水电基地是中国在黄河上游地区开发的重要水利工程群,其安全监测具有至关重要的作用。因此,本文基于黄河上游水电基地GNSS自动监测网开展实验,从GNSS高程拟合方法、GNSS数据处理策略和GNSS高程方向定位结果等方面详细论证。结果表明,GNSS拟合高程具有替代三等水准的可行性。

GNSS系统时间偏差参数分析

分析各GNSS在系统时差参数设计上的特点和变化,并以国际权度局(BIPM)和时间频率公报发布的数据为参考对GNSS播发的系统时差进行评估分析。结果表明,BDS播发的3种系统时差均存在十几ns的偏差,通过BDS间接获得的GLONASS与GPS、Galileo与GPS的系统时差准确度优于GLONASS和Galileo系统电文发播的同种时差参数。

新疆乌什7.1级地震前GNSS变形特征分析

2024年1月23日新疆乌什发生7.1级地震。为了研究震前GNSS变形特征,通过对比分析GNSS基线时间序列结果和区域应变结果,发现迈丹断裂带东西两段的地壳运动有所差异,东段的运动较强,乌什地震即发生在断裂带东段;利用4期速度场结果,计算得到动态应变场变化,从NS向应变场结果可以看出该区域的应变量值持续增加,应变持续在积累状态,从长期背景场可以看出7.1级地震发生在应变高值区的边缘;发震断层东西两侧的挤压滑动速率存在明显差异,西侧为(1.0±0.35)mm/a,东侧为(4.1±0.51)mm/a,且东侧的闭锁程度较高。研究认为迈丹断裂带两侧运动差异明显,乌什7.1级地震发生在滑动速率较高的东段,且该区域处于应变高值区的边缘。

GNSS辅助风云三号卫星MERSI近红外通道的大气可降水量反演方法

大气水汽是对流层中的重要参数之一,已被广泛应用于短临天气预警和长期气候监测等领域。我国风云三号(FY-3)系列卫星搭载的中分辨率光谱成像仪可用于大气水汽监测,但反演大气可降水量(PWV)时存在大气透过率参数低估、水汽与大气透过率回归系数经验选取的缺陷,无法满足在短临降雨监测、数值同化等高精度PWV应用方面的需求。针对该问题,本文提出一种GNSS辅助FY-3卫星的高精度PWV反演方法。本文方法引入高精度实测GNSS PWV作为大气透过率计算模型的回归拟合参数,辅助FY-3 L1级数据精确估计PWV和大气透过率的模型回归系数;同时,该方法顾及季节和高程因素对FY-3-L1 PWV反演的影响,分季节反演PWV并引入数字高程模型修正由于部分大气透过率参数低估导致的FY-3 L1 PWV相对不准确的现象。选取中国区域2013—2014年FY-3A卫星的L1数据和中国地壳运动观测网络的260个GNSS测站数据进行试验。结果表明,本文提出的GNSS辅助FY-3系列卫星PWV反演方法优于传统方法(FY-3A-L2 PWV),其整体精度改善率为74.5%,可得到更加可靠、稳健性更强的PWV格网产品,对于其在短临降雨监测和数值同化等方面具有重要意义。

因子图框架下里程计辅助GNSS/INS组合导航算法

在复杂观测环境下,GNSS/INS组合导航系统的GNSS信号易受干扰从而导致INS独立导航精度迅速下降。针对上述问题,本文基于因子图的里程计辅助GNSS/INS组合导航算法,利用里程计观测信息结合非完整性约束构建航向速度约束方程,同时采用能多次线性化计算和多次迭代的因子图优化方法进行参数估计。实际车载试验解算结果表明,在GNSS信号良好时,基于因子图方法比滤波方法具有更快的收敛时间,收敛速度提高了近10倍;在GNSS信号发生中断时,添加里程计辅助后组合导航系统在东向和北向分别提升了83%和89%。与传统的滤波融合手段相比,本文采用因子图优化后在东向和北向的定位精度分别有63%、70%的改善。

新疆及邻区现今GNSS变形特征与地震关系研究

基于GNSS观测数据,采用球面最小二乘配置方法计算了新疆及邻区的应变率张量特征,在统计分析研究区域应变率分布以及1900—2022年M≥6.0地震分布之间的关系的基础上,研究了GNSS应变率特征对强震地点的指示意义。通过构建三维弹性块体模型反演得到的区内主要断裂的运动变形特征,结合震源机制解结果,对比分析了断裂运动变形特征与不同区域强震类型之间的关系。结果表明:天山西段—帕米尔地区、阿尔金断裂带邻近地区呈现第二应变率高值特征,其中帕米尔构造结附近高值特性最明显;最大剪应变率方向在南天山西段—帕米尔地区主要为NE-NEE向,反映了该区以倾滑变形为主的特征。研究区域的M≥6.0地震主要分布在应变率高值区及其边缘,特别是帕米尔构造结东部地区的强震集中非常明显。区内断裂运动性质具有明显的分类特征,除整体以挤压运动为主外,NE走向断裂带以左旋走滑运动为主,NW走向的断裂以右旋走滑运动为主。NE走向的柯坪、迈丹和那拉提断裂带与NW走向的克孜勒陶、塔拉斯—费尔干纳断裂带汇集的南天山西段和帕米尔西构造结东部地区强震密集分布,强震的震源机制类型与断层运动方式较为一致。

基于自适应高斯渐进滤波的工程车GNSS/INS紧组合定位

研究了量测野值影响下的工程车GNSS/INS紧组合定位问题,提出了一种基于自适应高斯渐进滤波的车辆定位方法。首先,为降低量测野值对滤波器的破坏风险,利用假设检验方法对量测野值进行检测和剔除;其次,对于野值漏检测引起的定位性能下降的问题,设计了自适应的高斯渐进滤波方法来补偿量测的不确定性;特别地,利用线性化误差与系统估计误差的变化关系,对渐进量测更新方式进行了改进,从而实现对线性化误差的间接补偿。最后,通过工程车GNSS/INS紧组合定位实验进行结果分析,验证了所提方法的可靠性和优越性。

欧美月球GNSS规划现状分析综述

月球是地球最重要的天然卫星,当前国际上正在迎来新一轮月球探索高潮,数十个机构和商业团队正在规划月球探索任务,并设想在未来实现航天员长期驻月,围绕月球的“太空竞赛”刚刚开始。月球GNSS(基于现有的地球GNSS以及新的环月卫星通信导航基础设施的月球卫星通信导航定位技术)是空间基准科研的基础,能够提供航天器着陆定位以及月面(及其覆盖空间)定位、导航与授时等服务,同时可以将月球作为试验场,将导航工具包扩展到更远的目的地(如火星)。对欧美近期发布的月球GNSS规划进行了整理归纳,其中包括美国月球GNSS接收机实验(LuGRE)计划和欧洲月光(MoonLight)计划,以及美国中远期月球通信中继和导航系统(LCRNS)计划,这些计划可以为我国开展月球GNSS规划提供参考。

基于高度角随机模型的GNSS外辐射源雷达定位算法

针对GNSS外辐射源雷达定位时不同卫星对定位的误差贡献不同的问题,提出基于高度角随机模型的定位算法,理论分析目标位置估计量的克拉美罗界和统计特性,并计算卫星位置误差和地面站位置误差对定位误差的影响。仿真结果表明:所提出算法对不同GNSS卫星的直射、反射路径的伪距差测量值误差进行了合理分配,定位性能达到了克拉美罗界,且不会因为选星方案的改变而大幅恶化。对地面站位置误差和卫星位置误差的分析表明:地面站位置的标准差小于10 cm、卫星位置的标准差小于1 km时对定位总误差的贡献可以忽略不计。

基于GNSS的西秦岭北缘断裂带现今活动特征研究

基于1999~2007年、2009~2013年、2013~2017年和2017~2021年共4期GNSS地壳运动速度场构建GNSS速度剖面,分析西秦岭北缘断裂带各次级断裂现今地壳差异运动特征,并进一步建立负位错模型反演获取各次级断裂现今闭锁程度与滑动亏损速率。结果表明:1)西秦岭北缘断裂带现今整体呈现出以左旋走滑为主、兼逆冲挤压的活动特征。2)1999~2007年,锅麻滩段和天水-宝鸡段整体处于强闭锁状态,漳县段和鸳凤段仅部分区段闭锁且闭锁程度较低,闭锁深度也较浅;2009~2013年,西秦岭北缘断裂带中段闭锁程度有所减弱,鸳凤段东部与天水-宝鸡段东部由较强闭锁转变为蠕滑状态,锅麻滩段和天水-宝鸡段中西部依然呈强闭锁状态;2013~2017年,西秦岭北缘断裂带整体处于较强闭锁状态,仅天水-宝鸡段东部呈蠕滑状态;2017~2021年,锅麻滩段中西部、漳县段、鸳凤段东部和天水-宝鸡段中部处于较强闭锁状态,鸳凤段中西部与天水-宝鸡段西部则呈蠕滑状态。3)各次级断裂滑动亏损速率整体分布特征与断裂闭锁程度基本一致。西秦岭北缘断裂带锅麻滩段和天水-宝鸡段中部现今处于较强闭锁状态,具有较强的应变能累积背景。

基于新型SQM的GNSS欺骗式干扰检测技术

GNSS在基础设施应用的定位、导航、授时领域具有重要的战略意义.鉴于GNSS信号落地功率极低、民码结构透明等特点,民用卫星信号极易受到干扰和欺骗攻击,使得GNSS在获得广泛应用的同时也受到严重的干扰问题.本文针对传统信号质量监测(signal quality monitoring,SQM)检测量检测概率低和可靠性差的问题,提出一种无需使用跟踪支路载波相位信息的新型SQM检测量,将检测数据值进行滑动平均处理,减少异常波动值造成检测虚警率增高的情况,并推导了检测量的统计分布特性,设置在无先验信息下的计算门限与测量门限,能够避免出现在欺骗与真实导航卫星信号相对载波相位为π的整数倍时,检测失效的情况.在美国德克萨斯大学奥斯汀分校的公共数据库TEXBAT(texas spoofing test battery)的实采信号上进行的对比实验结果表明,所提基于I、Q支路能量变化的双重门限SQM检测算法在不同实采信号场景下均能够在较短的时间内以较优的准确度检测出欺骗攻击.研究成果对未来抗欺骗通信设备开发具有一定的参考价值,不仅能够有效提高检测性能,且无需对接收机硬件结构进行大规模的改变.进行大规模的改变.

GNSS卫星轨道机动探测技术进展

针对轨道机动探测是各种空间任务的共性关键技术,是全球卫星导航系统(GNSS)精密定轨定位数据处理的首要工作,在卫星导航领域具有重要的研究意义,尤其是中国多星座构型的北斗卫星导航系统,轨道机动频繁,影响更为严重的现状,研究分析全球卫星导航系统(GNSS)卫星轨道机动探测技术的进展:概述轨道机动的概念、机动方式和机动时间;归纳整理目前GNSS卫星轨道机动探测中常用的技术方法,包括基于卫星轨道的探测方法、基于卫星广播星历的探测方法以及基于观测值的探测方法;总结各类卫星轨道机动探测方法的特点,并统计分析GNSS卫星的轨道机动频次与时段,指出随着GNSS卫星轨道机动探测方法的不断完善,实时及事后卫星轨道机动探测问题都得到了显著改善,促进了GNSS服务性能的进一步提升;最后,总结现有轨道机动探测方法的优势与局限性,展望GNSS轨道机动卫星数据处理中尚须进一步解决的重要问题。