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971.
Hu Youhao Wang Hai Yazdani Amirmehdi Man Zhihong 《Neural computing & applications》2022,34(7):5241-5253
Neural Computing and Applications - This paper proposes a novel extreme learning machine (ELM)-based fixed time adaptive trajectory control for electronic throttle valve system with uncertain... 相似文献
972.
Neural Computing and Applications - In this paper, the state estimation problem is investigated for a class of discrete-time complex-valued neural networks (CVNNs) with mixed time delays. We... 相似文献
973.
吉林一号卫星测控采用USB测控体制,遥控接收采用FFT+DPLL1+DPLL2的架构,FFT主要实现对载波的粗捕,DPLL1在FFT的基础上实现对载波相位的精跟踪,DPLL2实现副载波的跟踪。对遥控副载波跟踪所用到的数字PLL技术进行了研究,首先给出了载波多普勒折算到副载波上的方法,然后对模拟PLL数字化进行了详细的论述,并设计了遥控副载波同步用的PLL2,对其稳定性、快捕带及快捕时间、捕获带和捕获时间、同步速率等进行了分析和仿真。结果表明,该方法具有捕获时间短、跟踪精度高、稳定性好等特点,易于数字化实现,已成功在吉林一号系列卫星中得到应用。 相似文献
974.
975.
Cui Ying Guo Dongyan Shao Yanyan Wang Zhenhua Shen Chunhua Zhang Liyan Chen Shengyong 《International Journal of Computer Vision》2022,130(2):550-566
International Journal of Computer Vision - Visual tracking of generic objects is one of the fundamental but challenging problems in computer vision. Here, we propose a novel fully convolutional... 相似文献
976.
Applied Intelligence - Support vector machine is one of the most extensively used machine learning algorithms. A typical application scenario of support vector machine classification is the... 相似文献
977.
建立了1个快速测定纺织品中有害有机溶剂残留量的超高效液相色谱/静电场轨道阱高分辨质谱(UPLC/Orbitrap HRMS)方法,该方法以乙醇为萃取溶剂,100℃下微波萃取纺织品中残留的有害有机溶剂,萃取液直接进行UPLC/Orbitrap HRMS,提取离子色谱峰面积外标法定量。对样品的提取条件、分析条件进行了优化。该方法的定量限为0.5μg/kg~10.0μg/kg。在3个不同加标浓度水平下,方法的平均加标回收率为81.8~94.5%,相对偏差偏差为3.8%~10.5%(n=9)。该方法简便快速,灵敏度高,定量限低,可有效地解决纺织品中残留的有害有机溶剂的快速测定问题。 相似文献
978.
The formation mechanism of surface texture for feed-direction ultrasonic vibration?assisted milling (UVAM) was investigated in this study by establishing a kinematic model and a pressing model of UVAM. The kinematic model showed that the cutter tip, which was supposed to be totally sharp, produced closed scratches by crossed trajectories. The variation trends of the interval for closed textures were of sine function. A comparative experiment was carried out by UVAM and conventional milling. A dividing line close to the X coordinate divides the surface feature into two parts. The pressing model showed that the tool minor cutting edge left clear traces with certain width because of the tool minor cutting edge angle. Scratches by tool minor cutting edge were intermittent and regularly varied when feed-direction vibration was introduced. All the surface feature changes are in the radial direction and the trajectory intersections shall always be the scratch grooves or ridges. The ratio between ultrasonic vibration frequency and spindle speed, tool radius, and the located cutter rotation angle affected the changing rule of scratches by tool minor cutting edge. The analytical models and the experimental results proved to each other reasonable. 相似文献
979.
Saeid?NezamabadiEmail author Thanh?Hai?Nguyen Jean-Yves?Delenne Farhang?Radjai 《Granular Matter》2017,19(1):8
Soft-grain materials such as clays and other colloidal pastes share the common feature of being composed of grains that can undergo large deformations without rupture. For the simulation of such materials, we present two alternative methods: (1) an implicit formulation of the material point method (MPM), in which each grain is discretized as a collection of material points, and (2) the bonded particle model (BPM), in which each soft grain is modeled as an aggregate of rigid particles using the contact dynamics method. In the MPM, a linear elastic behavior is used for the grains. In order to allow the aggregates in the BPM to deform without breaking, we use long-range center-to-center attraction forces between the primary particles belonging to each grain together with steric repulsion at their contact points. We show that these interactions lead to a plastic behavior of the grains. Using both methods, we analyze the uniaxial compaction of 2D soft granular packings. This process is nonlinear and involves both grain rearrangements and large deformations. High packing fractions beyond the jamming state are reached as a result of grain shape change for both methods. We discuss the stress-strain and volume change behavior as well as the evolution of the connectivity of the grains. Similar textures are observed at large deformations although the BPM requires higher stress than the MPM to reach the same level of packing fraction. 相似文献
980.
Tao Shen Hailong Dai Mingxin Song Hongchen Liu Xinlao Wei 《Journal of Superconductivity and Novel Magnetism》2017,30(4):937-941
Y3?xCe x Fe5 O 12 (CeYIG) ceramics, with x = 0, 0.15, 0.25, 0.35, 0.45, and 0.5, were fabricated by a conventional ceramic sintering technique. We studied the structures and magnetic fields of a series of CeYIG ceramics using X-ray powder diffraction, a scanning electron microscope, and a superconducting quantum interference device magnetometer. Findings showed that the substitution limit of the concentration of Ce3+ ions in the yttrium iron garnet structure was approximately x = 0.25. An extra CeO2 phase was detected in the ceramic when the addition of CeO2 content overtook the limit. The lattice constants and relative densities increased by increasing the Ce3+ contents in the ceramics. First, the saturation magnetization increased gradually with increases in the substitute concentration of Ce3+ ions and then decreased gradually when x = 0.35, 0.45, and 0.5. Overall, this study showed that the Y3?xCe x Fe5 O 12 material with x ≤ 0.15 exhibited excellent magnetic properties. Hence, the material show promise for magneto-optical and microwave communication applications. 相似文献