Small Target Recognition and Tracking Based on UAV Platform

Target recognition and tracking based on multi-rotor UAVs have the advantages of low cost and high flexibility. It can monitor low-altitude targets with high intensity. It has great application prospects in national defense, military, and civil fields. The existing algorithms for aerial small target recognition and tracking have the disadvantages of slow speed, low accuracy, poor robustness, and insufficient intelligence. Aiming at the problems of existing algorithms, this paper first makes a lightweight improvement for the YOLOv4 network recognition algorithm suitable for small target recognition and tests it on the VisDrone dataset. The accuracy of the improved algorithm is increased by 1.5% and the speed is increased by 3.3 times. Then, by analyzing the response value, the KCF tracking situation is judged, and the template update of the adaptive learning rate is realized. When the tracking fails, the target is re-searched and tracked based on the recognition results and the similarity judgment. Finally, experiments are carried out on the multi-rotor UAV, and the adaptive zoom tracking strategy is designed to track pedestrians, cars, and UAVs. The results show that the proposed algorithm can achieve stable tracking of long-distance small targets

Characterization of Pollutant Emissions from Typical Material Handling Equipment Using a Portable Emission Measurement System

Non-road equipment has been an important source of pollutants that negatively affect air quality in China. An accurate emission inventory for non-road equipment is therefore required to improve air quality. The objective of this paper was to characterize emissions from typical diesel-fueled material handling equipment (loaders and cranes) using a portable emission measurement system. Instantaneous, modal, and composite emissions were quantified in this study. Three duty modes (idling, moving, and working) were used. Composite emission factors were estimated using modal emissions and time-fractions for typical duty cycles. Results showed that emissions from loaders and cranes were higher and more variable for the moving and working modes than the idling mode. The estimated fuel-based CO, HC, NO, and PM2.5 composite emission factors were 21.7, 2.7, 38.2, and 3.6 g/(kg-fuel), respectively, for loaders, and 8.7, 2.4, 28.3, and 0.3 g/(kg-fuel), respectively, for cranes. NO emissions were highest and should be the main focus for emission controls. CO, HC, NO, and PM2.5 emissions measured were different from emission factors in the US Environmental Protection Agency NONROAD model and the Chinese National Guideline for Emission Inventory Development for Non-Road Equipment. This indicates that improving emission inventory accuracy for non-road equipment requires more real-world emission measurements

Design of a Control System for a Maglev Planar Motor Based on Two-Dimension Linear Interpolation

In order to realize the high speed and high-precision control of a maglev planar motor, a high-precision electromagnetic model is needed in the first place, which can also contribute to meeting the real-time running requirements. Traditionally, the electromagnetic model is based on analytical calculations. However, this neglects the model simplification and the manufacturing errors, which may bring certain errors to the model. Aiming to handle this inaccuracy, this paper proposes a novel design method for a maglev planar motor control system based on two-dimensional linear interpolation. First, the magnetic field is divided into several regions according to the symmetry of the Halbach magnetic array, and the uniform grid method is adopted to partition one of these regions. Second, targeting this region, it is possible to sample the electromagnetic forces and torques on each node of the grid and obtain the complete electromagnetic model in this region through the two-dimensional linear interpolation method. Third, the whole electromagnetic model of the maglev planar motor can be derived according to the symmetry of the magnetic field. Finally, the decoupling method and controller are designed according to this electromagnetic model, and thereafter, the control model can be established. The designed control system is demonstrated through simulations and experiments to feature better accuracy and meet the requirements of real-time control

Apollo: Adaptive Polar Lattice-Based Local Obstacle Avoidance and Motion Planning for Automated Vehicles

The motion planning module is the core module of the automated vehicle software system, which plays a key role in connecting its preceding element, i.e., the sensing module, and its following element, i.e., the control module. The design of an adaptive polar lattice-based local obstacle avoidance (APOLLO) algorithm proposed in this paper takes full account of the characteristics of the vehicle’s sensing and control systems. The core of our approach mainly consists of three phases, i.e., the adaptive polar lattice-based local search space design, the collision-free path generation and the path smoothing. By adjusting a few parameters, the algorithm can be adapted to different driving environments and different kinds of vehicle chassis. Simulations show that the proposed method owns strong environmental adaptability and low computation complexity

Processing of coal fly ash magnetic spheres for clay water flocculation

The application of coal fly ash magnetic spheres (MSs) in water treatment is limited due to their complex mineral compositions, low magnetism, and large diameters. In this study, MSs were carefully ball milled and magnetically separated to improve their related properties. After the processing, the resultant magnetic ball-milled MSs (MBMSs) show a substantial change in composition, magnetism, and surface property in addition to a decrease in diameter. Compared with those of the original MSs, the Fe percentage, magnetism, and specific surface area of MBMSs are increased by 25.87%, 54.60%, and 810%, respectively. Dispersive spectrometer mapping investigation shows segregated high- and low-Fe areas with different structures in MS. These different structures enable purification. Highly turbid clay water flocculation experiments using MSs as f locculants indicate that MBMSs can cause fast flocculation whereas the compared samples exert less or slight flocculation effect. Zeta potential investigation suggests that the different flocculation effects are due to the change in the point of zero charge (pH PZC ). The pH PZC increases from 3.91 for the original MS to 4.96 for MBMS. The reduction in the diameter, as well as the increase in magnetism, surface area, and pH PZC , makes MSs applicable to water treatment

Deep learning-based digital subtraction angiography image generation

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The precipitate evolution in friction stir welding of 2195-O Al–Li alloy

The precipitate evolution of friction stir welding (FSW) 2195-O Al–Li alloy was analyzed by back scattered electron (BSE), X-ray diffraction (XRD), differential scanning calorimetry (DSC) and transmission electron microscopy (TEM). Efforts were made to explore the correlation between precipitates and hardness, tensile properties of the FSW joints and discuss the reasons for the generation of a serration shape pattern. It can be found that the base material (BM) consists of large coarse equilibrium precipitates, such as θ, TB, T2, T and Al7Cu2Fe, which change a little in the heat affection zone (HAZ) and the thermo-mechanically affected zone during FSW. Whereas, these precipitates significantly decrease in the nugget zone (NZ) with many δʹ/βʹ, TB and GP zones generating. The FSW joints are fractured in the HAZ/BM, developing a joint coefficient of 99% and the decrease of elongation from 20.6% to 15%. Within the NZ, these coarse precipitates completely disappear in the advancing side (AS-NZ), while remain a lot in the retreating side (RS-NZ) with evidently decrease in content and size. Therefore, the increment of hardness decreases from the AS- NZ to RS-NZ. The develop of serration shape pattern is attributed to distribution difference of coarse equilibrium precipitates in content and size