Latest ArticlesThe accuracy and confidence level of the unmanned aerial vehicle(UAV) landing range are of great significance for objectively assessing the UAV’s ground risk. The uncertain wind field and complex electromagnetic environment are the main causes of uncertainty regarding UAV failure and landing range. Given the particle assumption in the case of complete failure of the UAV, firstly, a dynamic model of the UAV trajectory descent with the initial position and velocity as the boundary value and the wind speed vector and the initial position as random variables was constructed, and the failure and landing range of the UAV were determined by Monte Carlo simulation. Secondly, a geometric method for determining the envelope of the UAV ground risk buffer was proposed, and the quantitative determination of the ground risk buffer of the entire UAV track was realized. Finally, the method proposed was verified by taking an aerial inspection route as example and compared with the buffer protection area of the UAV in different wind fields and under various operating conditions, the effect of uncertain wind field and its operating conditions on the ground crash range of the UAV was studied, and the ground risk buffer zone under different operating conditions was established. The results show that falling at higher speed and higher altitudes under stronger winds yields a wider impacting area and a larger ground risk buffer.
ARGs(antibiotic resistance genes) as emerging environmental pollutants threaten human health, and studies show that secondary effluent from sewage treatment plants is an important source of ARGs in the environment. Ozone pre-oxidation combined with PAC(powdered activated carbon) and UF(ultrafiltration) was used to treat the secondary effluent from the wastewater treatment plant, and the factors and mechanisms of O3 dosage, pH, and temperature on the removal of different forms of ARGs in the secondary effluent were investigated. The results show that ARGs could be more effectively removed by PAC adsorption and UF after oxidative inactivation by O3; under the condition of optimal O3 dosage (2.0 mg/L), the combined O3-PAC-UF process could remove different types of ARGs (tetA, tetC, tetG, sulI, sulII) and other pollutants (intⅠ1, 16S rRNA) from the secondary effluent. The removal of different types of ARGs (tetA, tetC, tetG, sulI, sulII) and other pollutants (intⅠ1, 16S rRNA) by the combined process is 102.67~103.92 copies/mL, and the removal of cellular and free ARGs is significantly enhanced; the elevated pH and lower temperature facilitate the removal of ARGs; the direct oxidation of O3 molecules dominate the removal of ARGs in the secondary effluent. In conclusion, ozone combined with PAC and UF can effectively remove antibiotic resistance genes from secondary effluent.
To evaluate the safety of navigation flight task scheduling schemes in forest fire rescue, safety evaluation indicators for navigation rescue task scheduling schemes were proposed by detecting the flight path conflicts of various general aircraft. Using an airspace grid model to model the rescue flight environment, and planning the rescue flight paths of aircraft with different performance constraints based on their respective task scheduling schemes, and conducting trajectory conflict detection to evaluate the safety of the task scheduling scheme. The simulation results show that this method has a 53.8% improvement in time efficiency compared to the direct conflict detection algorithm, and a 6.7% improvement in accuracy compared to the efficient spatiotemporal synchronous route conflict detection method. It can be seen that this method can efficiently and accurately predict track conflicts in rescue flights and evaluate the safety of task scheduling schemes, providing effective decision support for navigation rescue command and scheduling work.
Muscle dysfunction, as one of the common extrapulmonary manifestations of COPD (chronic obstructive pulmonary disease), limits the exercise capacity, cardiorespiratory health, and quality of life of COPD patients, leading to poor prognosis. PBMT (photobiomodulation therapy) an emerging adjunctive treatment for COPD-related muscle dysfunction, has been widely promoted and utilized in clinical practice. It positively affects muscle inflammation, alleviates muscle fatigue, improves muscle metabolism, enhances muscle endurance, and accelerates muscle healing. The comprehensive review of the rehabilitation mechanisms and current application status of PBMT (photobiomodulation therapy) in addressing COPD (chronic obstructive pulmonary disease)-related muscle dysfunction, both domestically and internationally, is conducted to offer insights and guidance for the application of PBMT in the rehabilitation treatment of COPD-related muscle dysfunction.
The issue of soil erosion in the Loess Plateau was addressed, with a comprehensive analysis of the application and evolution of vegetation restoration technologies for loess slopes. The text highlights that vegetation restoration serves as an effective method to mitigate soil erosion and rejuvenate ecological functions. Vegetation restoration not only enhances soil stability but also boosts the ecological quality of slopes and contributes to the sustainable development of ecosystems. Considering the geographical characteristics of the Loess Plateau and the factors contributing to soil erosion, a review of the research history and current progress of vegetation restoration techniques in China was conducted. Detailed discussions on methods such as spray seeding and slope coverage restoration, each characterized by distinct benefits and drawbacks, were included. These techniques were selectively implemented based on specific site conditions and environmental characteristics, and were continuously refined to address any arising challenges during their application. Furthermore, the document outlined future directions for advancing vegetation restoration technology, stressing that a thoughtful integration of plant species selection, soil matrix enhancement, and technological innovation is essential for improving the ecological restoration outcomes on slopes. The adoption of modern technological tools like remote sensing and artificial intelligence for monitoring and managing geological hazards was recommended to enhance the effectiveness and accuracy of ecological restoration efforts. Finally, an interdisciplinary approach was advocated to spur innovative developments in slope management and ecological restoration technologies, with the goal of achieving ecological sustainability in the Loess Plateau.
In order to evaluate the quality of professional athletes in martial arts, the camera array based measurement and multi-view geometry were combined to develop a refined recognition method of human movements under the constraints of human parametric model, and a quantitative evaluation method system of martial arts movements was established based on the obtained joint position and angle information, and the technical movements of athletes of different levels in the five-step boxing event were measured and evaluated. The results show that the method developed in this paper can effectively realize the identification and quality evaluation of athletes’ movements in Wushu events, and the research results can also be extended to other competitive sports and public health, so as to provide support for scientific training and sports rehabilitation.
Aerodynamic principles and the assumption of axial inextensibility of a two-dimensional flexible plate were used to derive a nonlinear theoretical model of flag flutter, investigate and analyze the coupled motion characteristics of flexible flag and airflow in nature and wind energy collection fields, and examine the effects of length, mass ratio, and wind speed on its motion characteristics. The flag oscillation process in the wind was numerically simulated using the bidirectional fluid-structure coupling method and the overlapping mesh methodology, from which the features of the surrounding flow field and the motion behavior of the flag inside it were determined. The findings indicate that while swing displacement increases and subsequently declines with wind speed, the crucial flutter wind speed lowers as flag length increases. The chirp frequency decreases as the mass ratio increases, and the Strahl number is less affected. With the predefined dimensions of the flag, at low wind speeds, both the displacement and frequency of the swing are low. However, when the wind speed exceeds the critical vibration threshold, a significant vibration phenomenon occurs. Changes in surrounding pressure and velocity are caused by the flag-encircling vortex as it progresses through phases of formation, shedding, and disappearing. Numerical simulation techniques based on the overlapping mesh methodology successfully address the deformation problem of flexible flags. Theoretical and numerical simulations can be verified and analyzed with this method.
The physical properties lower limits of oil-gas charging in tight sandstone reservoirs are identified through a large number of core test and analysis data. The Chang8 reservoir types, pore-throat structure, and physical properties were clarified. Methods such as oil-gas occurrence, displacement pressure, physical property statistics, oil recovery index, and minimum pore-throat radius were employed to determine the current reservoir physical properties lower limit. By integrating the period of hydrocarbon accumulation and pore evolution, the critical physical properties during oil-gas charging were inverted. The results show that the reservoir types of Chang 8 are mainly feldspar sandstone and lithic feldspar sandstone in Fuxian area, with complex pore-throat relationship. These reservoirs are classified as tight reservoirs with low to extra-low porosity and extra-low to ultra-low permeability. It is preferred that the physical properties lower limits of the current reservoir are 7.0% and 0.15 mD, respectively. For inversion of oil-gas charging in Phase I (192.5~152.0 Ma), the lower limits of physical properties are 20.8% and 7.37 mD, respectively, for oil-gas charging in Phase II (152.0~126.0 Ma), the lower limits of physical properties are 8.2% and 0.22 mD. For oil-gas charging in Phase III (65.0~36.5 Ma), the lower limits of physical properties are basically consistent with the current lower limits of physical properties. The research findings provide an significant geological basis for the evaluation of reservoir and the prediction of favorable in the study area.
The total organic carbon content in shale reservoirs is a crucial parameter for assessing hydrocarbon generation potential and shale gas enrichment. Accurate prediction of TOC(total organic carbon) is essential for oil and gas exploration and development. Conventional linear regression methods are limited in their predictive accuracy due to the complex nonlinear relationships among regional and well logging data. To address this issue, a prediction model based on Adaboost-WOA-BP was proposed for predicting TOC content. This model integrates WOA(whale optimization algorithm) optimized Backpropagation neural networks as weak learners within the Adaboost framework to construct a strong learner. Use of optimal natural gamma, density, acoustic time difference, and other sensitive logging parameters associated with TOC content calculation as inputs for the prediction model. Compared to conventional linear regression, BP neural networks and WOA-BP neural networks, the Adaboost-WOA-BP model demonstrates higher predictive accuracy, achieving a 95% match between predicted and measured TOC values.
Pavement runoff could enter the karst aquifer system through sinkholes, karst windows, karst pools in karst areas, which could influence the karst water environment quality. Consequently, it is necessary to study the hydrochemical environment characteristics of pavement runoff in karst areas. Pavement runoff of Yaji, Qingshuiqiao and Baizhujing were sampled, characteristics of hydrochemical compounds and their influencing factors, hydrochemical environment quality were analyzed using multiple statistical method, Nemerow index method and comprehensive pollution index method. External influencing factor has small influences on the common hydrochemical ions, while has great influences on these trace elements. The compounds influencing the water environment of pavement runoff were nutrient compounds (NH3-N, TP, CODMn), landscape compound (suspended solids) and metal compounds (Mn, Hg and TFe) by analyzing the concentrations of hydrochemical compounds of pavement runoff. These compounds have close relationships with pavement behaviors, surrounding vegetations, traffic flow and came from fuel, lube, slop oil, gasoline, worn tyre and vegetations. Four main factors with the cumulative variance contribution rate of 97.99% were extracted from the monitoring dataset using the factor analysis method. It could be known from the four main factors that carbonates weathering was the main source of hydrochemical compounds of pavement runoff, the second was the particles of atmospheric and pavement influencing the SS of pavement runoff, the third was the human activities including pavement behaviors and protective measures of surrounding vegetations. Hydrochemical environment quality of Qingshuiqiao, Yaji and Baizhujing decreased in turn by using the Nemerow index method and comprehensive pollution index method. Hydrochemical environment quality of Baizhujing were poorest, which had potential risks for the water ecological environment, the pavement runoff could be reused for the surrounding vegetations through reasonable measurements. The results could not only provide scientific instructions for the treatment measures of pavement runoff, but also provide scientific evidences for the reasonable exploitation and utilization of karst water resources.