Spatio-Temporal Patterns of Fitness Behavior In Beijing Based on Social Media Data

Using social media data, this paper employs FastAI, Latent Dirichlet Allocation (LDA) and other text mining techniques coupled with GIS spatial analysis methods to study temporal and spatial patterns of fitness behavior of residents in Beijing, China, from the perspective of residents’ daily behavior. Using LDA theme model technology, it is found that fitness activities can be divided into four types: running-based fitness; riding-based fitness; fitness in sports venue; and fitness under professional guidance. Emotional analysis revealed that, residents can get a better fitness experience in sports venues. There are also obvious differences in the spatio-temporal distribution of the different fitness behaviors. Fitness behavior of Beijing residents has a multi-center spatial distribution pattern, with a wide coverage in northern city areas but obvious aggregation areas in southern city areas. In terms of temporal patterns, the residents' fitness frequency shows an obvious periodic distribution (weekly and 24 hours). And there are obvious differences in the time distribution of fitness behaviors for each theme. Additionally, based on the attribution analysis of a geodetector, it is found that the spatial distribution of fitness behavior of residents is mainly affected by factors such as catering services, education and culture, companies and public facilities.

Microseismic Response Characteristics Induced by Mining Activities: A Case Study

For deep coal mines, geological disturbances or mining activities can cause damage to coal and rock masses, easily inducing dynamic disasters such as rock bursts or coal and gas outbursts, which seriously threaten the safety production of coal mine. In this paper, first, the Liyazhuang Coal Mine introduced the SOS MS (Sensor Observation Service Microseismic) monitoring system from the Polish Research Institute and verified the accuracy of its positioning. Then, to study the characteristics of MS signals induced by different mining activities, based on the field monitoring results, the waveform and frequency spectrum characteristics of MS signals at different energy levels induced by different mining activities are analyzed, and the energy levels of MS signals caused by different mining activities are classified. Studies have shown that there are large differences in the waveform and spectral characteristics of MS signals at different energy levels. High-level energy seismic signals are characterized by large amplitudes, low frequencies, relatively concentrated distribution, long vibration duration, and slow attenuation. In addition, the relationship between mining activities and MS events is also statistically analyzed based on the spatial and temporal distribution of MS events with the advancement of working face, and the results show that the increase of vibration frequency and energy can be precursor information for roof pressure. With the advance of the working face, the MS energy has the characteristic of periodic distribution, which is consistent with the periodic weighting revealed by the working resistance of the support. This study provides a reference for further revealing the energy release mechanism of rock burst.

Nilpotency and periodic points in non-uniform cellular automata

Nilpotent cellular automata have the simplest possible dynamics: all initial configurations lead in bounded time into the unique fixed point of the system. We investigate nilpotency in the setup of one-dimensional non-uniform cellular automata (NUCA) where different cells may use different local rules. There are infinitely many cells in NUCA but only a finite number of different local rules. Changing the distribution of the local rules in the system may drastically change the dynamics. We prove that if the available local rules are such that every periodic distribution of the rules leads to nilpotent behavior then so do also all eventually periodic distributions. However, in some cases there may be non-periodic distributions that are not nilpotent even if all periodic distributions are nilpotent. We demonstrate such a possibility using aperiodic Wang tile sets. We also investigate temporally periodic points in NUCA. In contrast to classical uniform cellular automata, there are NUCA—even reversible equicontinuous ones—that do not have any temporally periodic points. We prove the undecidability of this property: there is no algorithm to determine if a NUCA with a given finite distribution of local rules has a periodic point.

Elastic cloaking for a periodic distribution of parallel finite cracks

We achieve elastic cloaking for a periodic distribution of an infinite number of parallel finite mode III cracks by means of the complex variable method and the theory of Cauchy singular integral equations. The cloaking bimaterial structure is composed of an undisturbed uniformly stressed left half-plane perfectly bonded via a wavy interface to the right half-plane which contains periodic cracks. The original design of the wavy interface and the positions of the periodic cracks are ultimately reduced to the solution of a Cauchy singular integral equation which can be solved numerically.

Serrated Chip Formation Induced Periodic Distribution of Morphological and Physical Characteristics in Machined Surface During High-Speed Machining of Ti6Al4V

Difficult-to-cut materials are widely used in aerospace and other industries. Titanium alloys are the most popular ones among them due to their high strength-to-weight ratio and high temperature resistance. However, in high-speed machining, the alloys are prone to produce serrated chips, which have a serious influence on surface integrity. In this study, a coupled Eulerian–Lagrangian method is used to simulate the orthogonal cutting of Ti6Al4V due to its advantages of avoiding element distortion and improving the data extraction efficiency. The internal relationship between serrated chip formation and periodic profile of machined surfaces is analyzed by the simulation results and experimental data which are obtained by optical microscope and white light interferometer. Furthermore, thermal–mechanical loads on machined surfaces are reconstructed based on the simulation results, and a coupled finite element and cellular automata approach is used to describe the dynamic recrystallization process within the area of the machined surface during the formation of a single serration. According to the results, the periodic fluctuation of cutting forces is attributed to the serrated chip formation phenomenon, which then leads to the periodic profile of machined surfaces. The period is about 60–70 µm, and its amplitude decreases with the increase of cutting speeds. Moreover, the loads on machined surfaces also show the same period due to serrated chip formation. As a result, the grain refinement layer thickness (about 2 ∼ 5 µm) in machined surfaces is related to the surface temperature and exhibits the same periodic characteristics along the cutting direction.

The periodic axon membrane skeleton leads to high-density sodium nanodomains but does not impact action potentials

ABSTRACTRecent work has established that axons have a periodic skeleton structure comprising of azimuthal actin rings connected via longitudinal spectrin tetramer filaments. This structure endows the axon with structural integrity and mechanical stability. Additionally, voltage-gated sodium channels follow the periodicity of the active-spectrin arrangement, spaced ∼190 nm segments apart. The impact of this periodic sodium channel arrangement on the generation and propagation of action potentials is unknown. To address this question, we simulated an action potential using the Hodgkin-Huxley formalism in a cylindrical compartment but instead of using a homogeneous distribution of voltage-gated sodium channels in the membrane, we applied the experimentally determined periodic arrangement. We found that the periodic distribution of voltage-gated sodium channels does not significantly affect the generation or propagation of action potentials, but instead leads to high-density sodium channel nanodomains. This work provides a foundation for future studies investigating the role of the voltage-gated sodium channel periodic arrangement in the axon.

Catalytic activity of CuGHK peptide-based porous material

Room temperature one-step synthesis of the peptide-based porous material with a periodic distribution of pockets decorated with lysine side chain active sites behaves as a heterogeneous organocatalyst. The pockets are...