Spatial distribution of clustered seismicity in Khibiny Montains

<p>Using long-term mining-induced earthquake statistics of the Khibiny Mountains (Kola Peninsula, Russia) we studied the spatial peculiarities of clustered seismicity. To declutter the earthquake catalog, we used the nearest neighbor method by Zaliapin and Ben-Zion, 2016, DOI: 10.1093/gji/ggw300. It was shown that the distribution of distances from triggering event to triggered earthquakes obeys a power law with a parameter independent of the trigger magnitude. This result is consistent with distribution of mainshock-aftershock distances obtained for tectonic seismicity by many researchers (e.g., Huc M., Main, DOI: 10.1029/2001JB001645; Felzer and Brodsky, DOI: 10.1785/0120030069; Richards-Dinger et al., DOI: 10.1038/nature09402). Combining the spatial power distribution and the law of earthquake productivity by Shebalin et al. 2020 (DOI: 10.1093/gji/ggaa252), confirmed for the seismicity of the Khibiny Mountains (Baranov et al., 2020, DOI: 10.1134/S1069351320030015) we derived a distribution of maximal distances from trigger to triggered earthquake.</p><p>Using this distribution, we suggest a probabilistic model of zone where triggered earthquakes are expected. The zone is a cylinder centered on the trigger hypocenter, its size (radius and height) depends on the probability of containing triggered earthquakes. The model validation was performed using Molchan’s error diagram. Applying the method of three strategies (Baranov and Shebalin, 2017, DOI: 10.1134/S1069351317020021) to the error diagram, we identified three limiting points on the error trajectory, corresponding to "soft," "neutral," and "hard" strategies. These strategies reflect the prediction importance.</p><p>The research was supported by Russian Foundation of Basic Research, Project No 19-05-00812.</p>

UJI EKSPERIMETAL TRAJECTORY TRACKING PADA ROBOT PENJINAK BOM

Masalah terorisme yang melanda dunia berimplikasi pada peperangan terhadap terorisme secara global. Penciptaan robot penjinak bom yang mampu menjinakkan bom secara handal dimaksudkan untuk menciptakan keamanan pada seluruh bidang serta pelayanan terhadap umat manusia. Tujuan dari penelitian ini adalah untuk menghitung error trajectory tracking pada robot penjinak bom. Robot penjinak bom ini menggunakan roda caterpillar dengan menggunakan dua motor dengan sistem kendali independen. Selain itu robot diuji cobakan dengan menggunakan kendali wireless dan navigasi denganlLine follower sistem. Pengujian dilakukan dengan membuat dua buah track lintasan pada permukaan lantai selanjutnya menguji sistem navigasi dengan kontrol manual melibatkan dua operator, kemudian penulis mengimplementasikan program sistem kendali robot penjinak bom menggunakan sensor garis. Kesimpulan yang dapat diperoleh dari penelitian ini adalah sistem kontrol dengan menggunakan wireless dan line follower dapat digunakan secara bergantian dimana nilai error untuk line follower sistem jauh lebih kecil dibanding dengan menggunakan sistem kontrol langsung (bluetooth).

Nonlinear Control of an Active Magnetic Bearing with Output Constraint

In this paper, an appropriate control strategy is proposed to handle the nonlinear dynamics ofan active magnetic bearing (AMB). The goal of the control design is to drive the AMB rotor to the origin with improved transient response. In order to achieve this task, back stepping control technique with a barrier Lyapunov function are employed to keep the tracking error trajectory inside a predefined zone to avoid possible mechanical contact between rotor and stator. Besides, a speed observer is also used since information about rotor speed is not always available. The stability of the closed-loop system is proven. The effectiveness of the proposed control strategy is verified by numerical simulations.

Evaluation of the Dynamic Performance for Five-Axis CNC Machine Tools Based on RTCP

RTCP (rotation tool center point), which is one of the necessary functions for high-grade CNC machine tools, can effectively decrease nonlinear errors caused by the motion of the rotation axis and improve the accuracy of the machinery. Based on the characteristic that the cutting tool tip point is relative to the manufacturing workpiece, the RTCP trajectory is proposed to conveniently measure the displacement of the tool tip point. The scheme is utilized to study the dynamic performance of machine tools, and a simulation that shows the relationship between the tool tip error trajectory and the factors influencing the dynamic performance of the machine tool is presented based on the servo system model. Then, the experiment is carried out, and the tool tip point error variation is found to be consistent with the simulation result. This study provides theoretical support for dynamic performance detection of five-axis CNC machine tools.