Frequency characteristics and far-field effect of gravity perturbation before earthquake

We used high-pass filtering and the Fourier transform to analyze tidal gravity data prior to five earthquakes from four superconducting gravity stations around the world. A stable gravitational perturbation signal is received within a few days before the earthquakes. The gravitational perturbation signal before the Wenchuan earthquake on May 12, 2008 has main frequency of 0.1–0.3 Hz, and the other four have frequency bands of 0.12-0.17 Hz and 0.06-0.085 Hz. For earthquakes in continental and oceanic plate fault zones, gravity anomalies often appear on the superconducting gravimeters away from the epicenter, whereas the stations near the epicenter record small or no anomalies. The results suggest that this kind of gravitational perturbation signals correlate with earthquake occurrence, making them potentially useful earthquake predictors. The far-field effect of the gravitational perturbation signals may reveal the interaction mechanisms of the Earth’s tectonic plates. However, owing to the uneven distribution of gravity tide stations, the results need to be further confirmed in the future.

Dynamic-Response Analysis of the Branch System of a Utility Tunnel Subjected to Near-Fault and Far-Field Ground Motions in Different Input Mechanisms

There are few studies on the dynamic-response mechanism of near-fault and far-field ground motions for large underground structures,especially for the branch joint of a utility tunnel(UT)and its internal pipeline.Based on the theory of a 3D viscous-spring artificial boundary,this paper deduced the equivalent nodal force when a P wave and an SV wave were vertically incident at the same time and transformed the ground motion into an equivalent nodal force using a self-developed MATLAB program,which was applied to an ABAQUS finite element model.Based on near-fault and far-field groundmotions obtained fromtheNGA-WEST2 database,the dynamic responses of a utility tunnel and its internal pipeline in different inputmechanisms of near-fault and far-field groundmotions were compared according to bidirectional input and tridirectional input,respectively.Generally,the damage to the utility tunnel caused by the near-fault ground motion was stronger than that caused by the far-field ground motion,and the vertical ground motion of near-fault ground motion aggravated the damage to the utility tunnel.In addition,the joint dislocation of the upper and lower three-way joints of the pipeline in the branch systemunder the seismic action led to local stress concentrations.In general,the branch system of the utility tunnel had good seismic performance to resist the designed earthquake action and protect the internal pipeline fromdamage during the rare earthquake.

Effect of far-field flow on a columnar crystal in the convective undercooled melt

The growth behavior of a columnar crystal in the convective undercooled melt affected by the far-field uniform flow is studied and the asymptotic solution for the interface evolution of the columnar crystal is derived by means of the asymptotic expansion method. The results obtained reveal that the far-field flow induces a significant change of the temperature around the columnar crystal and the convective flow caused by the far-field flow accelerates the growth velocity of the interface of the growing columnar crystal in the upstream direction and inhibits its growth velocity in the downstream direction. Our results are similar to the experimental data and numerical simulations.

Far-field analysis of effects of unilateral rupturing fault on the space correlation of strong ground motion

On the assumption that seismic source is simplified as linear rupture fault with finite length, this paper qualitatively studies the seismic source effects on space correlation of strong ground motion. Based on expanding expression of Fourier spectrum of strong ground motion with space coordinate variables, this paper also gives a expression of describing correlation of strong ground motion field. According to far-field condition, the theoretical formula of the expression can be obtained. Furthermore, this paper presents a theoretical formula of estimation the radius of strong ground motion field, which depends on expansion condition of Fourier spectrum of strong ground motion, with space variables. At last, taking one earthquake as an example, this paper gives three-dimension patterns of radius of the field with epicenter distance and azimuth as well as frequency.

Prediction Model of Abutment Pressure Affected by Far-Field Hard Stratum Based on Elastic Foundation Theory

In view of the three-dimensional dynamic abutment pressure,the influence of the far-field hard stratum(FHS)in deep,thick coal seams is indeterminant.Based on elastic foundation theory,a three-dimensional dynamic prediction model of the abutment pressure was established.Using this model,the dynamic change in the coal seam abutment pressure caused by the movement of the FHS was studied,and a method for determining the dynamic change range of the abutment pressure was developed.The results of the new prediction model of the abutment pressure are slightly higher than the measured values,with an error of 0.51%,which avoids the shortcomings of the results because the Winkler foundation model results are lower than the measured values and have an error of 9.98%.As time progresses,the abutment pressure and its distribution range are affected by the FHS movement,which has the characteristics of gradually increasing dynamic change until the FHS fractures.The peak value of the abutment pressure increases linearly with time,and the influence range increases with time following a power function with an exponent of less than 1.The influence range of the FHS movement on the abutment pressure ahead of the working face,behind the working face,and along the working face is 10 times,25 times,and 17 times the mining thickness,respectively.According to the actual geological parameters,the dynamic change range of the coal seam abutment pressure was determined by drawing an additional stress curve and by determining the threshold value.These research results are of great significance to the partition optimization of the roadway support design of deep,thick coal seams.

FFS重膜包装线常见故障原因分析及处理

在现代工业生产中,包装技术的效率和精确性对产品质量和生产成本有着直接的影响。FFS(Form-Fill-Seal)重膜包装线作为一种高效的自动化包装解决方案,广泛应用于化工、食品、医药等多个行业。尽管FFS重膜包装线在自动化和高效包装方面具有显著优势,但在实际运行过程中仍然会遇到各种各样的故障问题。文中探讨热封效果差、开袋效果差、手抓夹紧及料门插袋问题以及码垛问题等常见故障的成因及其处理方法,并总结经验以供今后参考。

Far-Field Pattern Reconstruction from Positioning Errors Affected Near-Field Data Acquired via Helicoidal Scanning

In this paper, an effective technique to compensate the positioning errors in a near-field—far-field (NF-FF) transformation with helicoidal scanning for elongated antennas is presented and validated both numerically and experimentally. It relies on a nonredundant sampling representation of the voltage measured by the probe, obtained by considering the antenna as enclosed in a cylinder ended in two half-spheres. An iterative scheme is used to reconstruct the helicoidal NF data at the points fixed by the representation from the acquired irregularly spaced ones. Once the helicoidal data have been retrieved, those needed by a classical NF-FF transformation with cylindrical scanning are efficiently evaluated by using an optimal sampling interpolation algorithm. Some numerical tests, assessing the accuracy of the approach and its stability with respect to random errors affecting the data, are reported. Experimental tests performed at the Antenna Characterization Lab of the University of Salerno further confirm the validity of the proposed technique.

神经肽FF调节由巨噬细胞组成的功能网络

目的神经肽FF(NPFF)是一种调节各种细胞过程的八肽,尤其是疼痛感知。最近,人们越来越有兴趣了解NPFF在神经内分泌炎症中的调节作用。本综述旨在全面概述巨噬细胞介导的生物过程中NPFF的调控。方法深入研究NPFF对巨噬细胞极化、自我更新调节和线粒体自噬促进的影响,促进从产热脂肪向储脂脂肪组织的转变。此外,还探讨了巨噬细胞介导的炎症反应的NPFF依赖性调节,其对巨噬细胞分化的影响,以及其诱导巨噬细胞转录组改变的能力。还讨论了NPFF作为神经内分泌炎症领域治疗分子的潜力。结论这篇综述提供了对以前未探索的神经内分泌炎症领域以及NPFF在这种情况下的调节作用的见解。总体而言,本工作提供了NPFF对巨噬细胞影响的理解,有助于探索其在未来研究中的药理学意义。

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.

Rockburst proneness considering energy characteristics and sample shape effects

Accurate prediction of rockburst proneness is one of challenges for assessing the rockburst risk and selecting effective control measures.This study aims to assess rockburst proneness by considering the energy characteristics and qualitative information during rock failure.Several representative rock types in cylindrical and cuboidal sample shapes were tested under uniaxial compression conditions and the failure progress was detected by a high-speed camera.The far-field ejection mass ratio(FEMR)was determined considering the qualitative failure information of the rock samples.The peak-strength energy impact index and the residual elastic energy index were used to quantitatively evaluate the rockburst proneness of both cylindrical and cuboidal samples.Further,the performance of these two indices was analyzed by comparing their estimates with the FEMR.The results show that the accuracy of the residual elastic energy index is significantly higher than that of the peak-strength energy impact index.The residual elastic energy index and the FEMR are in good agreement for both cylindrical and cuboidal rock materials.This is because these two indices can essentially reflect the common energy release mechanism characterized by the mass,ejection velocity,and ejection distance of rock fragments.It suggests that both the FEMR and the residual elastic energy index can be used to accurately measure the rockburst proneness of cylindrical and cuboidal samples based on uniaxial compression test.

基于FF总线技术工厂管控网的应用研究

通过对工厂管控网的相关情况、现场总线技术的应用价值以及基于FF总线技术的工厂管控网设计与应用进行深入研究,揭示该技术在工业领域的重要性和实际应用。研究结果可以为工厂自动化控制系统的优化提供有力支持,为工业领域的工厂自动化控制系统的应用提供有益的参考和借鉴。

FF 91试驾体验报告:科技感十足,动力性能确实优越

距离2023年8月12日法拉第未来宣布正式交付首辆FF 912.0 Futurist Alliance给首位塔尖用户至今,法拉第未来(FF)总共向市场交付了10辆FF 912.0 Futurist Alliance,其中一辆是向FF创始人兼首席产品和用户生态官贾跃亭完成交付。2023年5月份,FF 912.0版本正式发布,车型分为FF 912.0、FF 912.0未来主义者版、FF 912.0未来主义者联盟版。其中FF 912.0未来主义者联盟版售价为30.9万美元,折合人民币约219.5万,且全球限量300台。

基于FF总线型电动执行机构应用分析

FF型总线多用于液位、流量、压力及气动定位器数据传输与监视,电动执行机构由于自身系统的冗余特性,通常使用Profibus-DP型总线对该类型设备进行数据采集与监视。通过对FF型总线电动执机构进行相关的案例应用分析,并结合FF型总线的特点,通过上层管理软件,实现对FF型总线电动执机构的远程诊断、控制、故障处理、数据及曲线分析。进而实现FF型总线电动执行机构的设备优化管理,并使该类型总线的电动执行机构得以推广应用,为后续电动执行机构选用FF型总线或Profibus-DP型总线提供了参考。

FF与Profibus现场总线在火电厂的应用研究

借助实验室基本的、完整的FF和Profibus系统,分别对两类现场总线技术进行了以工程应用为目的的试验、分析和研究,对两类现场总线技术特点及其在火电厂的适用范围进行了阐述,并对某大型火电厂的Profibus现场总线控制系统的设计、开发、试验进行了总结。

FF HSE和FF H1协议网关的基本原理与实现

研究了通过协议转换式网关实现不同总线协议之间互联和互操作的基本原理 ,解决了在开发FFHSE和FFH1网关软件过程中的多个关键技术 .FF一致性测试软件包的测试结果表明该网关符合FF协议标准 .

基于FF协议的智能气动阀门定位器开发

介绍了自主开发的基于 FF协议的智能气动阀门定位器 ,具体阐述了 FF智能气动阀门定位器的硬件设计、软件设计以及 FF通信的实现。文中对

中国股票市场FF多因子模型的比较分析

FF多因子模型是资产定价理论的重要模型,它对于中国股市是否也同样适用呢?我们针对上证180指数样本股和深证100指数样本股以及二者之和分别建立了FF多因子模型,并进行了检验和比较分析。使用的方法是最小二乘法和广义距估计方法(GMM)。结果表明FF多因子模型对于中国股市是基本适用的。

取代查尔酮衍生物非线性光学性质的FF/PM3理论计算

利用有限场FF/PM 3方法讨论了查尔酮类化合物的非线性光学性质 ,针对不同取代基和取代位置系统分析了分子结构、取代基的类型、取代位置对共轭有机分子电子性质及非线性光学性质的影响 .结果表明 。

二甲苯蓝FF分光光度法测定微量亚硝酸根

研究了在稀盐酸介质中微量亚硝酸根与二甲苯蓝ＦＦ发生的亚硝化反应，建立了测定微量亚硝酸根的新方法。方法的线性范围为 ０．２× １０－６～ １５ × １０－６ ｇ／２５ ｍＬ ＮＯ２－，其 Ｓａｎｄｅｌｌ灵敏度为９．１５× １０－１０ｇ／ｃｍ２。方法已用于水中微量亚硝酸根的测定，并对反应机理进行了初步探讨。

华电莱州电厂基于FF和Profibus现场总线的水网控制系统

结合华电莱州电厂水网控制系统,总结了FF和Profibus-DP现场总线用于火电厂水网控制的设计要点。该控制系统以美国艾默生过程控制有限公司的OvationDCS为平台,对FF和Profibus-DP 2种现场总线协议进行了合理配置,实现了对水网的控制。同时,对2种现场总线技术在控制系统调试过程中易出现信号干扰、主站与从站参数设置错误等问题,提出了解决方案。