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905.
针对无线传能系统宽频段电场辐射屏蔽的需求,建立了采用主动屏蔽方式的无线传能系统屏蔽效能分析电路模型。推导出主动屏蔽激励源可由无线传能系统电压激励源控制。给出了空间点位置和面位置屏蔽效能计算公式,通过对激励电压源进行傅里叶变换后提取关注频段电压分量可实现对宽频段屏蔽效能的分析。通过仿真分析证明了方法的有效性,屏蔽效能与空间位置有关,同时受限于传输效率的约束。通过调节压控电压源的压控系数可以在传输效率损失相对较小的情况下实现关注位置电场辐射的有效屏蔽。最后通过实验验证了无线传能系统主动屏蔽方式屏蔽效能分析方法的正确性和工程可应用性。 相似文献
906.
This paper compares the flame acceleration in single-trial dual-detonation tubes triggered by a spark plug and non-thermal plasma igniter. The low-temperature plasma was generated by an in-house novel AC-driven dielectric barrier discharge igniter, which reduces the power supply requirements and was applied in the quiescent ignition of a single-trial detonation tube. Three different types of detonation mixtures were tested with flame propagation tracked by ion probes and pressure waves recorded by high-frequency pressure transducers. The flame propagation speeds were calculated and compared based on signals from the ion probes. The detonation combustion succeeded in the dual tubes, but the deflagration-to-detonation transition could be significantly accelerated by the plasma for all mixtures, as it was shortened by more than 50% compared to that of the spark plug. The present study provides a suitable technological approach for igniters of PDEs. 相似文献
907.
《中国航空学报》2020,33(2):448-455
The reliability of the on-wing aircraft Auxiliary Power Unit (APU) decides the cost and the comfort of flight to a large degree. The most important function of APU is to help start main engines by providing compressed air. Especially on the condition of sudden shutdown in the air, APU can offer additional thrust for landing. Therefore, its condition monitoring has drawn much attention from the academic and industrial field. Among the on-wing sensing data which can reflect its condition, Exhaust Gas Temperature (EGT) is one of the most important parameters. To ensure the reliability of EGT, one kind of data-driven anomaly detection framework for EGT sensing data is proposed based on the Gaussian Process Regression and Kernel Principal Component Analysis. The situations of one-dimensional and two-dimensional input data for EGT anomaly detection are considered, respectively. The cross-validation experiments are carried out by utilizing the real condition data of APU, which are provided by China Southern Airlines Company Limited Shenyang Maintenance Base. The anomalous stuck condition of EGT sensing data is also detected. Experimental results show that the proposed EGT sensing data anomaly detection method can achieve better performance of false positive ratio, false negative ratio and accuracy. 相似文献
908.
《中国航空学报》2020,33(11):2864-2876
The increasing gross weight of electric Unmanned Aerial Vehicle (UAV) poses a challenge in practical applications. The range and endurance of the electric UAV are limited by the fixed mass of the battery package. In this work, a design optimization method for the battery package topology of small electric UAV is proposed to enhance the performance. To improve the accuracy of the method, the dynamic battery model and simplified electric component models are presented. These models are utilized by the trajectory optimization method, which takes the dynamic characteristic into consideration to calculate the aircraft performance. The direct optimal control method is used for solving the trajectory optimization problem, and this method is tested on a small blended-wing-body electric aircraft. The test result shows that the range and energy-consumption are mainly influenced by the parallel topology of the battery package, while the flight time in climb phase is more sensitive to the series topology. It is deduced that the range- and energy-optimal design points can be considered concurrently in design optimization. The work proves the feasibility of integrating the trajectory optimization and battery package design. 相似文献
909.
910.
基于CDMA-TDD系统的联合功率控制算法 总被引:1,自引:0,他引:1
针对常规的码分多址CDMA (Code Division Multiple Access)时分双工TDD (Time Division Duplex) 系统功率控制算法存在的缺陷,提出了一种基于通信链路当前状态信息的联合功率控制算法.从理论上推导了联合功率控制方程.在新算法中,所有移动终端调整后的新发射功率值是基于共同的通信资源得出的.分配在同一时隙的各个移动终端的功率调整是基于通信链路的当前状态信息,其中包括各移动终端下一步使用的调整后的新发射功率值.使得各移动终端能够平等的共享链路资源,加快功率控制的收敛.通过建立功能模型,验证和评估了这一新的算法.仿真结果表明这一新的功率控制算法优于当前的常规算法,能减小接收端信噪比动态范围,降低干扰信号强度,提高能量效率和系统容量. 相似文献