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991.
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光电脉冲编码器四倍频电路的实现及其应用 总被引:15,自引:1,他引:14
就光电编码器的实际应用问题及解决方法,提出并设计了一套适用于精度要求较高的位移检测方法及实现电路。末以欠驱动器臂的控制为例,介绍其具体应用。 相似文献
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Yoshioki S 《Journal of molecular graphics & modelling》2008,26(8):1353-1364
Two model systems of methane hydrate are constructed. One has a small cage surrounded by 12 large cages. The other has a large cage surrounded by four small cages and ten large cages. Three different H-bonding network patterns between waters are formed, and three random configurations of methane in each cage are chosen. A new method called the surface water fixed model is presented in which the energy minimum conformations for both model systems are preserved close to the X-ray crystallized structure. With normal mode analysis, we calculated frequencies of 2916.6 cm−1 for a small cage at a centre, 2915.9 cm−1 not at a centre, and 2911.7 cm−1 for a large cage at a centre, and 2911.3 cm−1 not at a centre. These frequencies are in moderate agreement with the corresponding Raman spectra, though not adequate. With our new method, however, it should be possible to improve agreement with the Raman spectra, if a model system vastly larger than the present model systems were constructed. 相似文献
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Density functional calculations and minimization techniques have been employed to characterize the structural and electronic properties of [5,6]-heterofullerene-C58Si-C2v. Since it has odd number of atoms and a near planar tetracoordinate Si atom on the skeleton of the cage, it has odd number of atoms assembling a cage and is a novel molecule. Vibrational frequencies of the molecule have been calculated at the B3LYP/6-31G* level of theory. The absence of imaginary vibrational frequency confirms that the molecule corresponds to a true minimum on the potential energy hypersurface. Sixteen 13C nuclear magnetic resonance (NMR) spectral signals of C58Si are characterized, and its heat of formation was estimated in this work. 相似文献
997.
A virus coevolutionary partheno-genetic algorithm (VEPGA), which combined a partheno-genetic algorithm (PGA) with virus evolutionary theory, is proposed to place sensors optimally on a large space structure for the purpose of modal identification. The VEPGA is composed of a host population of candidate solutions and a virus population of substrings of host individuals. The traditional crossover and mutation operators in genetic algorithm are repealed and their functions are implemented by particular partheno-genetic operators which are suitable to combinatorial optimization problems. Three different optimal sensor placement performance index, one aim on the maximization of linear independence, one aim on the maximization of modal energy and the last is a combination of the front two indices, have been investigated. The algorithm is applied to two examples: sensor placement for a portal frame and a concrete arc dam. Results show that the proposed VEPGA outperforms the sequential reduction procedure (SRP) and PGA. The combined performance index makes an excellent compromise between the linear independence aimed index and the modal energy aimed index. 相似文献
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Jürgen Bohn 《Personal and Ubiquitous Computing》2008,12(2):155-166
We provide evidence of the feasibility and effectiveness of a middleware architecture for mobile devices (MoDs), which employs
dense distributions of small computerized entities for providing fault-tolerant location-aware services. We do so by describing
exemplary implementations based on radio frequency identification as an enabling technology. Firstly, we present prototypical
implementations of the hardware abstraction layer and of selected core middleware services. The latter enable a MoD to store
and retrieve data and position information in physical places in a fault-tolerant manner, and to identify places based on
a location abstraction which is robust against failure of individual tags. Secondly, we investigate the feasibility of some
higher-level services and applications by developing and evaluating prototypical systems for tracing and tracking, self-positioning,
and collaborative map-making.
相似文献
Jürgen BohnEmail: |
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介绍结构振动控制仿真分析软件TSHOW基于结构振动控制的算法和原理,建立了在无控、主动控制、隔振控制和半主动控制时结构运动的微分方程,并应用MATLAB控制系统工具箱(Control System Toolbox)中的函数,研制了仿真分析程序。对于实验结果,经TSHOW进行后处理,可以与仿真结果进行对比,从而分析控制实验的效果。仿真结果以图形方式显示,内容包括控制力时程、所选楼层的动力响应等,例如位移、速度、加速度时程。频域分析包括位移、速度、加速度的幅频响应曲线。所绘曲线的显示特性可以按照要求进行设置和调整。为了探求隔振层和控制装置的动力特性,利用图形技术,实现了层间恢复力-位移曲线的动态显示。 相似文献