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921.
不确定多变量线性系统的快速收敛Terminal滑模控制   总被引:1,自引:0,他引:1  
徐世许  马建敏 《上海航天》2011,28(2):7-11,62
针对一类不确定多变量线性系统,提出一种对数型快速Terminal滑模变结构控制方案,设计了对数型非线性Terminal滑模超曲面及其相应的变结构控制律.研究结果表明:系统状态在有限时间内收敛至Teminal 滑模面上,随后系统保持在滑模面上并在有限时间内收敛到平衡点.与普通快速Terminal滑模相比,在滑模面上能以更...  相似文献   
922.
热和振动复合环境中人体热调节的数值模拟   总被引:1,自引:0,他引:1  
本文针对热和振动复合环境对人体的影响特点,建立了该复合环境中二维人体热调节系统的数学模型.采用数值方法对人体热调节系统数学模型进行求解,计算了不同热和振动复合环境条件下人体温度分布及动态响应,计算结果与实验结果相符较好,相对误差小于5%.  相似文献   
923.
给出了拼音汉字转换的定义,并建立了一个带调拼音词句到汉字语句的自动转换系统。它由五个部分组成,自动分词模块,词法分析模块,句法和语义分析模块,语义修饰模块和显示模块。其中句法分析是系统的核心,在比较各种方法的基础上选择了扩充转移网络模型,使ATN的优点和音字转换的特点得到较好的结合,测试结果表明,系统的正确转换率达到97%。  相似文献   
924.
NONLINEARDYNAMICINVERSIONCONTROLWITHADAPTIVECOMPENSATIONFORFLIGHTCONTROLSYSTEMXuJun,ZhangMinglian,LiYouliang(DepartmentofAuto...  相似文献   
925.
介绍了黑龙江国防军工计量管理信息系统的设计及其应用。  相似文献   
926.
工作温度直接影响吸收式制冷系统的性能,而工作温度的选择受Gibbs相律和工质热力性质的限制。本文研究了NH3-NaSCN吸收式制冷系统的可能温度组合;有无回热器两种情况系统的热力参数和性能,如:吸收器和发生器中溶液浓度、循环倍率以及有无回热器时系统基于焓的性能系数等;分析了工作温度对系统性能的影响。结果表明,在无回热器时工作温度对系统性能的影响是不一致的。  相似文献   
927.
Multi-agent cooperation problems are becoming more and more attractive in both civilian and military applications. In multi-agent cooperation problems, different network topologies will decide different manners of cooperation between agents. A centralized system will directly control the operation of each agent with information flow from a single centre, while in a distributed system, agents operate separately under certain communication protocols. In this paper, a systematic distributed optimization approach will be established based on a learning game algorithm.The convergence of the algorithm will be proven under the game theory framework. Two typical consensus problems will be analyzed with the proposed algorithm. The contributions of this work are threefold. First, the designed algorithm inherits the properties in learning game theory for problem simplification and proof of convergence. Second, the behaviour of learning endows the algorithm with robustness and autonomy. Third, with the proposed algorithm, the consensus problems will be analyzed from a novel perspective.  相似文献   
928.
As aerospace vehicles travel in a hellish environment, the reliability of the measuring and controlling systems has played a critical role in the credibility of a whole airborne system. Embryo-electronic system is a bionic hardware capable of self-diag- nosing and self-healing. This article presents a new approach to design embryo-electronic systems and introduces their bionic principles, system structures and fault-tolerant mechanism. As the current methods cannot meet the requirements for large-scale embryo-electronic systems, this article advances a new shift-register-based configuration memory of embryonic system to solve the problem by using the inter-cell communication to reduce the gene storage capacity of a single cell. The article designs an overall structure of the shift-register-based configuration memories of the embryonic system and connects them into a chain structure. The article also designs an inner circuit of the cell, the control of shift-register-based configuration memory and the way of runtime dynamic configuration. The simulation of field programmable gate array (FPGA) evidences the realizability of the proposed design. Compared to the SRAM-based one, this memory can save 90% of the area when constructing embryonic systems larger than 128 × 128 under the same condition.  相似文献   
929.
Plant lighting is a critical issue for cost effectiveness of bioregenerative systems. A plant lighting system using sunlight has been investigated and compared to systems using electrical lighting. Co-generation of electricity and use of in situ resource utilization (ISRU) were also considered. The fixed part of equivalent system mass was found to be reduced by factors of from 3.1 to 3.9, according to the mission assumptions. The time-dependent part of equivalent system mass was reduced by a smaller value, of about 1.05. Cost effectiveness of bioregeneration has been compared to the cost of shipping food. Break-even times for different Lunar and Mars missions were generally in the order of 2–10 years, and were quite sensitive to the assumptions. There is significant scope for future refinement of these values, and work is ongoing.  相似文献   
930.
The James Webb Space Telescope   总被引:4,自引:0,他引:4  
The James Webb Space Telescope (JWST) is a large (6.6 m), cold (<50 K), infrared (IR)-optimized space observatory that will be launched early in the next decade into orbit around the second Earth–Sun Lagrange point. The observatory will have four instruments: a near-IR camera, a near-IR multiobject spectrograph, and a tunable filter imager will cover the wavelength range, 0.6 < ; < 5.0 μ m, while the mid-IR instrument will do both imaging and spectroscopy from 5.0 < ; < 29 μ m.The JWST science goals are divided into four themes. The key objective of The End of the Dark Ages: First Light and Reionization theme is to identify the first luminous sources to form and to determine the ionization history of the early universe. The key objective of The Assembly of Galaxies theme is to determine how galaxies and the dark matter, gas, stars, metals, morphological structures, and active nuclei within them evolved from the epoch of reionization to the present day. The key objective of The Birth of Stars and Protoplanetary Systems theme is to unravel the birth and early evolution of stars, from infall on to dust-enshrouded protostars to the genesis of planetary systems. The key objective of the Planetary Systems and the Origins of Life theme is to determine the physical and chemical properties of planetary systems including our own, and investigate the potential for the origins of life in those systems. Within these themes and objectives, we have derived representative astronomical observations.To enable these observations, JWST consists of a telescope, an instrument package, a spacecraft, and a sunshield. The telescope consists of 18 beryllium segments, some of which are deployed. The segments will be brought into optical alignment on-orbit through a process of periodic wavefront sensing and control. The instrument package contains the four science instruments and a fine guidance sensor. The spacecraft provides pointing, orbit maintenance, and communications. The sunshield provides passive thermal control. The JWST operations plan is based on that used for previous space observatories, and the majority of JWST observing time will be allocated to the international astronomical community through annual peer-reviewed proposal opportunities.  相似文献   
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