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61.
The low-thrust trajectory optimization with complicated constraints must be considered in practical engineering. In most literature, this problem is simplified into a two-body model in which the spacecraft is subject to the gravitational force at the center of mass and the spacecraft＇s own electric propulsion only, and the gravity assist （GA） is modeled as an instantaneous velocity increment. This paper presents a method to solve the fuel-optimal problem of low-thrust trajectory with complicated constraints in a full ephemeris model, which is closer to practical engineering conditions. First, it introduces various perturbations, including a third body＇s gravity, the nonspherical perturbation and the solar radiation pressure in a dynamic equation. Second, it builds two types of equivalent inner constraints to describe the GA. At the same time, the present paper applies a series of techniques, such as a homotopic approach, to enhance the possibility of convergence of the global optimal solution. 相似文献
62.
婴幼儿营养方便食品的研制 总被引：1，自引：0，他引：1
本文初步探讨了婴幼儿的营养特点，并分析了的婴幼儿的摄食特点，在此基础上结合国外部分婴儿食品的设计思路，充分开发利用我区优质的肉、奶、水果、蔬菜资源，针对性地开发研制了4种符合婴幼儿生理需要，并易于消化吸收的婴幼儿断奶食品或辅助食品。 相似文献
63.
64.
自改革开放以来,人民的生活水平得到了有效改善,汽车这一高消费交通用具已逐渐普及到户.但是大量的汽车在国内尤其是大中型城市中停车已成为严重的问题.物联网智能停车场以先进的现代技术以百万摄像机抓拍车牌读取车辆信息进而有效的让车主进出停车场,提高停车效率. 相似文献
65.
经过对停车诱导系统现状的研究,结合智能交通系统,设计了一个功能全面的智能停车诱导系统。系统采用分区诱导的策略,主要功能模块包括停车场数据采集、停车场数据处理与分析、管理中心数据发布及停车场数据接收等几个模块。采用比较流行的B/S模式对智能停车诱导系统进行管理,课题研究重点为车载诱导终端及停车场内停车诱导。 相似文献
66.
传统的信道估计方法往往假设多径分量数已知且为常数,粒子滤波算法可估计服从高斯分布的时变信道。实际无线环境中,多径分量数目与幅度皆为时变,则粒子滤波估计方法性能恶化。本文提出基于二进制粒子群算法和卡尔曼滤波的MIMO-OFDM信道混合估计方法。采用随机集建模MIMO信道,并分析得到其多径转移概率模型;基于此模型将信道分解为离散部分和连续部分,推导得到此两部分与整体信道关系;采用二进制粒子群算法拟合信道离散部分,利用卡尔曼滤波估计信道幅度,将利用信道估计计算得到的观测值与真实观测值的近似程度作为适应度函数。仿真结果表明:本文所提出的信道估计方法性能优于基本粒子滤波的信道估计方法。 相似文献
67.
Vassilis Gikas Constantinos Antoniou Guenther Retscher Athanasios Panagopoulos Allison Kealy Harris Perakis 《Journal of Location Based Services》2016,10(4):241-261
A relatively low-cost system for indoor parking facilities management is proposed, which is a combined solution of RFID/WiFi and a MEMS IMU monitoring scheme. An RFID localisation module is proposed in the form of so-called virtual gates. To define such virtual gates, either RFID tags or readers are placed at known locations throughout the area of interest. In this study, a number of tags are fixed at known positions and a moving reader is carried by each participating vehicle. Based on this configuration set-up, the Cell of Origin (CoO) technique is applied, in which the system indicates the presence of the user carrying the reader in a cell around the tag location. To define a virtual gate, tags are installed along the parking lot corridors and at critical transit passages in the parking facility. The CoO technique is also proposed in the case of WiFi for location determination of vehicles in a multi-storey car park. In this study, WiFi is employed to monitor the passing vehicles and bridge the gap until a tag can detect a user’s reader again. Thus, a combined positioning solution of RFID and WiFi is achieved. As a complement to the proposed RFID/WiFi system, this study examines the potential and limitations of MEMS IMU sensors (i.e. accelerometers, gyroscopes and barometers) commonly found in modern smartphones. The paper concludes with a detailed discussion on the implications of alternative positioning techniques for indoor parking management. 相似文献
68.
Keizo Nakayama 《Electronics and Communications in Japan》2019,102(8):17-24
For assist in color discrimination of color vision defects, the method of observing objects through colored filter has been known. If red filter, which absorbs mostly all light except red light, is used, only the red objects can be highly visible. In this paper, a Heilmeier type guest‐host liquid crystal device with magenta dye was applied to a filter type assist device for red‐green color vision defect. This device can easily control transmittance of green light by changing applied voltage, and make green objects perceived to flicker synchronously. The subjective appraisal of the assist device in color discrimination was performed by five participants with normal vision using a constructed experimental system using a video camera and a PC with a vision simulator. For the confusion indices of the Panel D‐15 test, the effect of the device was statistically significant at P < .01. Moreover, a participant with color vision deficiency assessed it and got results without color confusion on the Panel D‐15 test. 相似文献
69.
Dr. Jie Wang Dr. Chuanli Ma Dr. Linghao Su Dr. Liangyu Gong Dongqi Dong Dr. Zexing Wu 《ChemElectroChem》2020,7(22):4606-4613
Exploration of efficient strategies for highly capacitive electrodes is of great significance for the development of advanced energy devices. Herein, we propose a novel method for the preparation of a hierarchical porous carbon material derived from longan pulp biomass for application in supercapacitors. First, a precursor of the two-dimensional graphitized carbon with uniform carbon spheres is self-assembled via a hydrothermal method with a post-calcination process. After that, the longan pulp hierarchical porous carbon with inner pores is achieved through an embedding method with a mixture of precursor, KOH and KCl at high-pressure and appropriate annealing temperature by self-sacrificial means. The rich mesopores inside the sheet of LHPC-3 demonstrate a more conducive strategy to create holes inside the materials, which is beneficial for electrical double-layer capacitance. As a result, the LHPC-3 is characterized with a high specific surface area of 1678 m2 g−1 and an abundance of meso-/micropores, which facilitate the electrolyte penetration and mass transfer rates. Accordingly, LHPC-3 exhibits an excellent specific capacitance of 380 and 153 F g−1 at 0.5 A g−1 in three-electrode and symmetric supercapacitor systems, respectively. The new synthesis strategy is more conducive to the internal pore formation of carbon materials and has the potential to be widely applied to the synthesis of other electrochemical materials. 相似文献
70.
介绍磁助器的设计原则和方法，并成功地应用于准分子激光放电电路中，实验结果表明，设计的磁助器能在不显著影响激光输出能量情况下，减少高压快放电中开关器件─—闸流管的能量损耗，减小反向电流。 相似文献