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[Objective] To analyze the scale-dependent relationships between daily sediment yield and key environmental factors and to explore effective prediction method to cope with the prediction challenges caused by the complexity of sediment transport mechanisms and the nonlinearity of hydrological processes. [Methods] Employing the Composite Ensemble Empirical Mode Decomposition with Adaptive Noise (CEEMDAN) approach, we analyzed the multi-temporal scale variability characteristics between daily sediment yield and five potential influencing variables (flow rate, precipitation, average temperature, potential evapotranspiration, and NDVI) in the controled regions of four hydrological stations in the Fu River basin of Southwest China from 2013 to 2018. Interactions between daily sediment yield and related variables at different temporal scales were identified, upon which predictions of daily sediment yield were predicted. [Results] The CEEMDAN method successfully decomposed the daily sediment yield and its potential influencing variables into 10-11 intrinsic mode functions (IMFs) and residual item, revealing the significant changes of the daily sediment yield at different temporal scales ranging from 3 to 730 days. After decomposition, daily sediment yield showed significantly enhanced correlation with howrate and precipitation across all temporal scales, whereas temperature, potential evapotranspiration, and NDVI were primarily significantly correlated with long-term scale sediment yields. By using stepwise multiple linear regression to predict the daily sediment yield, the prediction performance of the model is significant, and the R2 values exceeds 0.55 at all stations. [Conclusion] The CEEMDAN method effectively revealed the scale dependency between sediment yield and its influencing variables, offering a new perspective for understanding the dynamics of river sediment transport.

To solve the problems of small local relief range, low continuity and high operational risk of rockburst, regional hydro-fracking and burst prevention system and engineering application research were carried out within thick and hard roof of a coal seam by well over thousand meters on and under the ground. The results show that, according to the loading conditions, the roof dominated rockburst can be divided into three types: superposed dynamic and static loading type, high static loading type and high static unloading type; The thick and hard roof is the main source of regional static and dynamic loading for rock burst initiation of mining surrounding rock. With the thick and hard roof as the target, which provides the source of dynamic and static load for rock burst initiation, a segmented fracturing pressure relief system for the roof with 1000 meter horizontal holes on and under the ground was established and fracking was carried out in this area. By destroying the integrity of the overlying roof in the burst prone area in advance on and under the ground, the load is transferred to the more intact roof area, so as to provide a low stress operational environment for underground excavation and extraction, and also make the rock burst initiation conditions inapplicable. The fracking and burst control tests on the roof area using the horizontal well drilled on the ground before the extraction of the panel, and underground drilling from the entries during the extraction were carried out respectively. Remarkable results have been achieved in practice, forming a new disaster prevention and control mode of “fracking before construction” for burst prone coal mines under construction, and “fracking before tunneling, fracturing before mining” for the producing coal mines.

In order to solve the problems of low pressure relief intensity, untimely pressure relief and high labor intensity in the prevention and control of rock burst by using large diameter borehole pressure relief in deep heading roadway, taking the 401103 withdrawal roadway of Mengcun Coal Mine in Binchang mining area of Shaanxi Province as the engineering background, the main control factors of rock burst are analyzed. It is considered that the strong rock burst tendency, large buried depth and fault structure of coal and rock layers are the main reasons of rock burst. Coal and rock layers have strong rock burst tendency, which makes the coal rock system capable of generating rock burst. The large buried depth of the working face leads to a high level of concentrated static load, which reduces the threshold for rock burst. The high concentrated static load in the main bearing area superimposes the concentrated dynamic load released by fault energy accumulation, which can easily induce shock start and lead to the appearance of rock burst. The use of blasting pressure relief to prevent rock burst is manifested in structural reconstruction, stress release and energy consumption. The implementation of blasting cracking in the peak area of the supporting pressure of the surrounding rock of the heading roadway can form a pressure relief protection zone in the surrounding rock of the roadway, thereby reducing the tendency of coal rock burst, weakening high concentrated stress, increasing rock burst energy consumption and reducing the risk of rock burst. For the 401103 withdrawal roadway, the blasting pressure relief scheme of roof, heading face and side are proposed. And the effect of pressure relief and anti-rock burst is tested by seismic wave CT detection and micro-seismic monitoring. The results show that after adopting the blasting pressure relief scheme, the area of the high stress area is reduced by 50%, and the stress concentration is significantly reduced. The average energy of microseismic events is significantly reduced, the energy is all less than 104 J. And there is no sharp change in the energy of microseismic events and the pressure relief effect is good.

In public, smoking behavior not only causes pathological harm to human health, but also exerts danger of fire hazards, etc. For the health and safety considerations, this paper designs a real-time smoking detection model based on deep learning for airports, gas stations, chemical warehouses and other places where smoking is strictly prohibited. This model uses a convolutional neural network to process the input frame from the video stream captured by the webcam. Through the process of image feature extraction, feature fusion, target classification and target posi-tioning, the coordinate of the cigarette is located, and then the smoking behaviors can be found out. Common object detection algorithms are not ideal for small target objects and the detection speed needs to be improved. This paper designs a series of convolutional neural network modules to reduce the amount of model parameters and pick up the inference speed to meet real-time requirements as well as improving the accuracy of small target object (cigarette) detection. This paper also comes up with some training skills to make the model more robust. Due to the lack of relevant dataset, this paper produces a dataset related to smoking behaviors. Through comparative experiments, it is proven that the algorithm proposed in this paper has better detection effects on proposed dataset and some public datasets.

In order to solve the safety problem of deep intelligent mining and prevention and control personnel threatened by rock burst, an intelligent prevention and control method of deep rock burst was put forward. Based on the key role of foundational static load inducing rock burst initiation, theoretical basis of intelligent prevention and control of deep rock burst was proposed, which was to automatically detect the foundational static load of surrounding rock in mining space, and achieve intelligent and precise decrease of its concentration degree, so as to improve threshold of acquiring static load or dynamic load increment in later stage for achieving purpose of rock burst prevention and control. Development paths of researching intelligent prevention and control of deep rock burst in the future were put forward, which included active schedule theory and method of multi-source information of rock burst disaster, expert database of disaster prevention scheme based on multi-source information fusion, rapidly interactive and intelligent robot and informationized equipment, intelligent control of rock burst disaster and compound disaster self-adaption technology and effect self-evaluation technology of major disaster prevention and control.

A novel printed ultra-wideband(UWB) slot antenna with reconfigurable band-notched characteristics for cognitive radio(CR) applications is presented. An improved rectangular monopole antenna is used as the basic model and a tangential rectangular floor is used to realize the ultra-wideband characteristics of 2.9～12 GHz. The band-notched function is achieved by etching one symmetric folded slot which consists of an inverted U-shaped slot and H-shaped slot on the modified rectangular radiation patch. By switching the pin-diodes to change the shape and effective length of the folded slot, the reconfigurable function is achieved. The antenna is compact and easy to process, and has potential application in CR system. Simulated and measured results obtained for the antenna show that it exhibits good radiation behavior and also has three reconfigurable frequency band-notched functions in the range of WiMAX(3.4～3.9 GHz), WLAN(4.6～6.0 GHz) and downlink of X-band satellite communication(6.5～8.2 GHz).

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The hot air anti-icing system is one of the important ways to prevent aircraft icing. Numerical simulation method was carried out to study the influence of the structural parameters on the thermal performance of the hot air anti-icing system. The hot air flow and heat transfer in the anti-icing cavities with different nozzle-to-surface height, number of the nozzle rows and hot air jet angle were simulated using the computational fluid dynamics (CFD) method. The thermal efficiency of the anti-icing system and the convective heat transfer coefficient distribution of the skin inner surface were obtained. The results show that; 1) with the increase of the nozzle-to-surface height in the range of 4mm to 36mm, the thermal efficiency of the anti-icing system reduces and the heat transfer performance of the hot air impinging on the surface weakens, 2) with consistent flow flux, the thermal efficiency of the anti-icing system increases from three to two nozzle rows, 3) the thermal efficiency improves with the 15° rotation of the hot air jet angle along the upper surface direction, indicating that the surface curvature effects the jet surface heat transfer performance. The results presented in this paper can help to the design of the anti-icing cavity. [ABSTRACT FROM AUTHOR]