In order to improve the effect of dance teaching action analysis, this paper uses dance action skill feature identification method to analyze dance teaching action and combines teaching and ...technology to simulate dance action. Moreover, this paper conducts dynamic modeling of dance movements and analyzes the typical properties of several dynamic modeling techniques. At the same time, this paper takes the double-joint dance movement limb as the control object for comparative analysis. The comparison shows that the fractional sliding mode approaching law has better smoothing properties. In addition, this paper selects the control method combining fractional calculus and sliding mode control theory to improve the tracking speed and following effect of the double joints of dance movements. Finally, this paper studies the variance virtual spindle cross-coupling control method based on fractional-order sliding mode to further improve the synchronization accuracy of dance movement limb joints. From the experimental data, it can be seen that the application effect of dance movement skill feature recognition in dance teaching movement analysis is very good.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The devastating Hunga Tonga-Hunga Ha’apai underwater volcano erupted at ~04:15 UT on 15 January 2022. We captured the waves that erupted from the volcano propagating in the ionosphere by monitoring ...total electron content (TEC) perturbations utilizing ground-based global navigation satellite system (GNSS) receivers that receive electromagnetic signals transmitted from the geostationary satellites operated by the BeiDou Navigation Satellite System (BDS). Meanwhile, ground barometers detected unusual enhancements of air pressure traveling in the troposphere. A novel phenomenon shows that the waves can individually propagate with a speed of ~335 m/s in the ionosphere, which is faster than its’ ~305 m/s in the troposphere. We further examined multiple geophysical data at the particular site of the novel instrumental array. Analytical results show that the pressure enhancements traveling in the troposphere not only downward trigger ground vibrations mainly in the horizontal components without obvious time difference, but also upward, leading the secondary TEC perturbations with a ~12-min delay.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
The sudden eruption of the Tonga underwater volcano (20.53°S, 175.38°W) on 15 January 2022 generated explosions that triggered blast waves traveling away from the eruption. In this study, the ...analysis of the geomagnetic field observations on the ground shows that the eruption perturbed the E‐region current density by 22–55 mA/m within a radius of 8,000 km away from the eruption. The perturbation evolved into large scales of ∼5 hr and thousands of kilometers as it traveled away. The traveling speed of the leading front is ∼740 m/s that is near acoustic in the ionosphere. The magnetic fields and total electron content observations suggest that the dynamics changes further induced significant ionospheric disturbances that lasted ∼10 hr after the eruption. The examination of the Tonga volcanic eruption inspires us that a near‐surface perturbation can change the dynamics of the upper atmosphere.
Plain Language Summary
As we drop a stone into the still water, the water piles up around the rock and induces ripples in the form of concentric circles that expand and travel away from the center point. A similar phenomenon happened in the atmosphere after the eruption of the Tonga underwater volcano (20.53°S, 175.38°W) at ∼04:15 UT on 15 January 2022. The Earth's atmosphere is a pond of air. The explosive eruption triggered prosperous waves, which is similar to dropping a stone into water. The waves, ripples, and disturbances in different spheres are fantastic due to the eruption (Figure S8 in Supporting Information S1). Besides the tsunamis, atmospheric concentric ripples, and ionospheric traveling disturbances, this study for the first time showed that the blast wave due to the eruption changed the dynamics of the ionosphere or thermosphere (upper atmosphere). It is well known that a significant volcanic eruption can release tremendous ashes and gases into the troposphere and stratosphere (lower atmosphere), which change the chemical and dynamic process there. The observations in this study surprisingly show that the eruption changed the dynamics of the upper atmosphere, where the volcanic cloud cannot reach.
Key Points
The eruption of the Tonga underwater volcano perturbed the E‐region current and, in turn, changed the geomagnetic field by ∼20–50 nT
A large near‐surface perturbation can modulate the ionospheric dynamics and further induce ionospheric disturbances
The significant ionospheric disturbances with periods ranging from several minutes to hours lasted more than 10 hr after the eruption
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Periodic signals replaced noise that was found in continuous seismic data, particularly in the nighttime, from the broadband seismometer at the MVP-LAI (monitoring vibrations and perturbations in the ...lithosphere, atmosphere and ionosphere) system before the occurrence of the Luxian earthquake on 16 September 2021. A short distance of ~150 km between the MVP-LAI system and the epicenter of the Luxian earthquake suggests the periodic singles as promising seismo-phenomena, due to that the radius of the earthquake preparation zone is ~380 km for an M6 event. Integration of geophysical parameters, including atmospheric pressure, vertical electric field, radon concentration, groundwater level and precipitation, at the MVP-LAI system provides an excellent opportunity for studying the seismo-LAI coupling associated with the Luxian earthquake. Analytical results show that ground vibrations, atmospheric pressure and total electron content varied from ~10−3 to ~10−2 Hz before the Luxian earthquake. The seismo-LAI coupling in the relatively low frequency band (~10−3 Hz) can be referred to as the acoustic-gravity waves triggered by the amplified ground vibrations. In contrast, the seismo-LAI coupling in a relatively high frequency band (~10−2 Hz) would be caused by micro-cracks and/or the high-mode natural frequency that further drives changes of TEC due to the atmospheric resonance.
Geostationary BeiDou satellites monitor the total electron content (TEC) in the ionosphere over certain locations 24 hr per day without interruption and act as ionosphere‐based seismometers. The ...system detected perturbations in TEC before both the M6.1 Dali and M7.3 Qinghai earthquakes that occurred during the night of 21–22 May 2021. The TEC perturbations reside mainly over an area within a distance of ∼700 km from the epicenters of the earthquakes. The standing waves revealed the persistence of a subsurface wave source before the occurrences of the earthquakes, which differs from the co‐seismic ionospheric distributions propagating away from the epicenters. The resident waves in TEC and ground vibrations share a frequency of ∼0.004 Hz, which can be attributed to the resonant coupling between the lithosphere and ionosphere.
Plain Language Summary
Large earthquakes seriously threat human life and induce economic loss. However, predicting an earthquake remains as a huge challenge due to the lack of reliable precursor signals. Something must be happened before a large earthquake. Therefore, we are looking for the reliable geophysical parameters for identifying the precursor that human beings are desired. In this study, the ionospheric total electron content (TEC) from the geostationary satellites of the Beidou global navigation satellite system system recorded an unusual phenomenon of TEC perturbations resides in a particular area that appeared after mid‐May in the post‐sunset hours over China. The unusual phenomenon is significantly different from the morphologies of the traveling ionospheric disturbances and plasma bubbles over Asia in summer. The TEC perturbations reside over both two areas within a distance of ∼700 km where cover the epicenters of the M6.1 Dali and M7.3 Qinghai earthquakes occurred during the night of 21–22 May 2021. The perturbations in TEC and ground vibrations share a frequency of ∼0.004 Hz, which can be attributed to the resonant coupling between the lithosphere and ionosphere during the earthquakes.
Key Points
Ground vibrations and total electron content (TEC) perturbations share a frequency of ∼4 mHz
Geostationary BeiDou satellites detected TEC wave prior to large earthquakes
TEC perturbations resided persistently around the epicenters
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Recognizing human movement is an important research topic in the field of human-computer interaction, and people expect it to be used in smart homes, virtual reality, and electronic games. Based on ...the interaction between humans and computers, more and more attention has been paid, especially in the field of smart home action recognition. Through observation, people can understand the intention of intelligent interaction is included in the main part. However, the current recognition algorithms still cannot meet the actual requirements of the accuracy, real-time and robustness of human motion recognition. Especially in order to recognize complex human movements in real time, it is imperative to solve several problems in motion capture and recognition. Establishing the feature parameter angle of the feature vector space of motion data, using the pre-recognition algorithm is based on multi-class support vector machines. The motion recognition algorithm takes advantage of the accurate and fast classification function of svm. Based on the structural differences of the motion data, most of the data can be correctly identified. The optimal motion recognition algorithm uses hmm to correct the svm error recognition result through the random constraint relationship between the error recognition data and the actual label. Based on data simulation and analysis, each variable determined by the grid search algorithm has the highest accuracy in the optimization of each variable of the support vector machine. Finally, a smart home simulation experiment interactive system was built, and a local database was created, including 1,300 processes. The real-time algorithm uses the data in the local database for training and testing. Experimental results show that the motion recognition algorithm in this paper improves the accuracy and robustness of complex motion recognition. While meeting the real-time recognition conditions, the correct answer rate of the final operation can reach 9.6%. The human motion trajectory recognition system uses the three-dimensional trajectory of gestures to recognize motion. The information in the three-dimensional space is more comprehensive, and the orbit recognition is more robust.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
The single index and generalized single index models have been demonstrated to be a powerful tool for studying nonlinear interaction effects of variables in the low-dimensional case. In this article, ...we propose a new estimation approach for generalized single index models
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BFBNIB, GIS, IJS, KISLJ, NUK, PNG, UL, UM, UPUK
To calibrate the helium mass-spectrometer leak detector in-site in the whole range, a series of leaks with helium-permeable membranes of different leakage rates were connected to a helium ...mass-spectrometer leak detector separately, then a set of readings of standard leaks were gained, and the relation curves were fitted mathematically between the standard leakage rates and leakage readings so as to give a fitting formula between the whole-range readings and leakage rates. As a result, the simplicity and efficiency method make it suitable for calibrations of helium mass-spectrometer leak detector.
In this paper, we propose a new dimension reduction method by introducing a nominal regression model with the hazard function as the conditional mean, which naturally retrieves information from ...complete data and censored data as well. Moreover, without requiring the linearity condition, the new method can estimate the entire central subspace consistently and exhaustively. The method also provides an alternative approach for the analysis of censored data assuming neither the link function nor the distribution. Hence, it exhibits superior robustness properties. Numerical studies show that the method can indeed be readily used to efficiently estimate survival models, explore the data structures and identify important variables.
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BFBNIB, GIS, IJS, INZLJ, KISLJ, NMLJ, NUK, PNG, SAZU, UL, UM, UPUK, ZRSKP
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