Application-Driven AI Paradigm for Human Action Recognition

Human action recognition in computer vision has been widely studied in recent years. However, most algorithms consider only certain action specially with even high computational cost. That is not suitable for practical applications with multiple actions to be identified with low computational cost. To meet various application scenarios, this paper presents a unified human action recognition framework composed of two modules, i.e., multi-form human detection and corresponding action classification. Among them, an open-source dataset is constructed to train a multi-form human detection model that distinguishes a human being's whole body, upper body or part body, and the followed action classification model is adopted to recognize such action as falling, sleeping or on-duty, etc. Some experimental results show that the unified framework is effective for various application scenarios. It is expected to be a new application-driven AI paradigm for human action recognition

Effect of corrosion on the bond behavior of steel-reinforced, alkali-activated slag concrete

Alkali-activated slag concrete (ASC) is regarded as one of the most promising sustainable construction materials for replacing ordinary Portland cement concrete (OPC) due to its comparable strength and outstanding durability in challenging environments. In this study, the corrosion of steel bars embedded in ASC and OPC was studied by means of an electrically accelerated corrosion test of steel bars in concrete. Meanwhile, the bond performance of the corroded steel bars embedded in ASC was tested and compared with corresponding OPC groups. The results showed that ASC and OPC behaved differently in terms of bond deterioration. The high chemical resistance of ASC decreased the corrosion of steel bars and, thus, increased the residue bond strength and the bond stiffness. © 2023 by the authors

Experimental and Statistical Study on Mechanical Characteristics of Geopolymer Concrete

This paper studies the statistical correlation in mechanical characteristics of class F fly ash based geopolymer concrete (CFGPC). Experimentally measured values of the compressive strength, elastic modulus and indirect tensile strength of CFGPC specimens made from class F fly ash (CFA) were presented and analyzed. The results were compared with those of corresponding ordinary Portland cement concrete (OPCC) using statistical hypothesis tests. Results illustrated that when possessing similar compressive and tensile strength, the elastic modulus for CFGPC is significantly lower than that of OPCC. The corresponding expressions recommended by standards for the case of OPCC is proved to be inaccurate when applied in the case of CFGPC. Statistical regression was used to identify tendencies and correlations within the mechanical characteristics of CFGPC, as well as the empirical equations for predicting tensile strength and elastic modulus of CFGPC from its compressive strength values. In conclusion, CFGPC and OPCC has significant differences in terms of the correlations between mechanical properties. The empirical equations obtained in this study could provide relatively accurate predictions on the mechanical behavior of CFGPC

Energy levels and radiative transitions of the K-shell excited sextet states in boron-like sulfur ion

Theoretical calculations are reported for energy levels and transition probabilities of the K-shell excited sextet series 6Se,o(m) and 6P,o,e(m)(m=1-7) for the astrophysically important element sulfur. Energy levels, fine structure splittings, and transition parameters of the high-lying sextet series 6Se,o(m) and 6P,o,e(m)(m=1-7) in boron-like sulfur ion are calculated with the multi-configuration Rayleigh-Ritz variation method. To obtain the accurate energy level, the relativistic corrections and mass polarization effect are included by using the first-order perturbation theory. Configuration structures of these sextet series are assigned according to the energies, percentage contributions of basis states to the eigenvector, relativistic effect corrections, and verification of fine structure splittings. The oscillator strengths, transition probabilities and wavelengths of electric-dipole transitions between 6So,e(m) and 6Pe,o(m) (m=1-7) states are also systematically calculated and discussed.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Evaluation of Comprehensive Emergency Capacity to Urban Flood Disaster: An Example from Zhengzhou City in Henan Province, China

In the context of climate change and urbanization, increasing flood disasters leads to severe losses and impacts on urban inhabitants. In order to enhance urban capacity to cope with floods and reduce losses, the comprehensive emergency-response capacity to flood disaster (CERCF) was studied in Zhengzhou City, which is seriously affected by floods. Firstly, the evaluation index system of flood emergency capacity was constructed from three aspects, including pre-disaster prevention capacity, during-disaster disposal capacity and post-disaster recovery capacity. Secondly, the weight of each index was calculated by the combination of the entropy weight method and the coefficient of variation method, and the evaluation model was established by the comprehensive index method. Thirdly, the CERCF of Zhengzhou City was classified into three grades by the Jenks natural-breakpoint classification method. Finally, the contribution model was used to reveal the contribution factors of flood emergency capacity in Zhengzhou city. The following beneficial conclusions were drawn: (1) The overall CERCF of Zhengzhou City was on a low level. The proportions of the study area at low, medium and high levels were 58.33%, 33.33% and 8.34%, respectively. Spatially, the CERCF was high in central regions and low in in the west and east parts of Zhengzhou City. (2) It was found that PDPC and PDRC made the greatest contribution, while DDDC has a relatively low contribution degree

Model Predictive Control for Automatic Carrier Landing with Time Delay

This paper focuses on the problem of automatic carrier landing control with time delay, and an antidelay model predictive control (AD-MPC) scheme for carrier landing based on the symplectic pseudospectral (SP) method and a prediction error method with particle swarm optimization (PE-PSO) is designed. Firstly, the mathematical model for carrier landing control with time delay is given, and based on the Padé approximation (PA) principle, the model with time delay is transformed into an equivalent nondelay one. Furthermore, a guidance trajectory based on the predicted trajectory shape and position deviation is designed in the MPC framework to eliminate the influence of carrier deck motion and real-time error. At the same time, a rolling optimal control block is designed based on the SP algorithm, in which the steady-state carrier air wake compensation is introduced to suppress the interference of the air wake. On this basis, the PE-PSO delay estimation algorithm is proposed to estimate the unknown delay parameter in the equivalent control model. The simulation results show that the delay estimation error of the PE-PSO algorithm is smaller than 2 ms, and the AD-MPC algorithm proposed in this paper can limit the landing height error within ±0.14 m under the condition of multiple disturbances and system input delay. The control accuracy of AD-MPC is much higher than that of the traditional pole assignment algorithm, and its computational efficiency meets the requirement of real-time online tracking

Structural impact damage of metal honeycomb sandwich plates

Dynamic response of sandwich plates with a metal honeycomb core under low-velocity impact has been investigated. Experiments of the fully clamped sandwich plates subjected to low-velocity impact of the drop-hammer with a hemispherical nose have been conducted and plastic failure modes have been measured. Structural damage mechanism of sandwich plates has been identified and explored. It is found that finite element simulations of these experiments are in good agreement with the experimental measurements. Analytical solutions for permanent deflections and peak impact forces are derived and capture the experimental results with reasonable accuracy. It is shown that the impact positions have important influence on the dynamic response of sandwich plates subjected to low-velocity impact. The impact resistance of sandwich plate decreases from the central position to the non-central positions

Evaluation of Comprehensive Emergency Capacity to Urban Flood Disaster: An Example from Zhengzhou City in Henan Province, China

In the context of climate change and urbanization, increasing flood disasters leads to severe losses and impacts on urban inhabitants. In order to enhance urban capacity to cope with floods and reduce losses, the comprehensive emergency-response capacity to flood disaster (CERCF) was studied in Zhengzhou City, which is seriously affected by floods. Firstly, the evaluation index system of flood emergency capacity was constructed from three aspects, including pre-disaster prevention capacity, during-disaster disposal capacity and post-disaster recovery capacity. Secondly, the weight of each index was calculated by the combination of the entropy weight method and the coefficient of variation method, and the evaluation model was established by the comprehensive index method. Thirdly, the CERCF of Zhengzhou City was classified into three grades by the Jenks natural-breakpoint classification method. Finally, the contribution model was used to reveal the contribution factors of flood emergency capacity in Zhengzhou city. The following beneficial conclusions were drawn: (1) The overall CERCF of Zhengzhou City was on a low level. The proportions of the study area at low, medium and high levels were 58.33%, 33.33% and 8.34%, respectively. Spatially, the CERCF was high in central regions and low in in the west and east parts of Zhengzhou City. (2) It was found that PDPC and PDRC made the greatest contribution, while DDDC has a relatively low contribution degree