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1.
An adaptive tracking design strategy based on quantized state feedback is developed for uncertain nonholonomic mobile robots with unknown wheel slippage effects. All state variables and control torques are assumed to be quantized by the state and input quantizers, respectively, in a network control environment. Thus, the quantized state feedback information is only available for the tracking control design. An approximation-based adaptive controller using quantized states is recursively designed to ensure the robust adaptive tracking against unknown wheel slippage effects where the quantized-states-based adaptive mechanism is derived to compensate for unknown wheel slippage effects, system nonlinearities, and quantization errors. The boundedness of the quantization errors and estimated parameters in the closed-loop system is analyzed by presenting some theoretical lemmas. Based on these lemmas, we prove the uniform ultimate boundedness of closed-loop signals and the convergence of the trajectory tracking error in the presence of wheel slippage effects. Simulations verify the effectiveness of the resulting tracking scheme. 相似文献
2.
现有的基于磁共振测量的嗅觉刺激器,通过调节嗅剂液体浓度的方法可以实现不同浓度的嗅觉刺激,但随着实验进行,受到嗅剂挥发以及实验环境(温度、湿度、气流量)变化的影响,很难确保输送至鼻腔的嗅剂气体浓度的稳定性,进而影响实验结果的准确性.本研究对本实验室前期开发的嗅觉刺激装置进行改进,实现了气体浓度精确定量.改进后的嗅觉刺激器主要分为三个部分:控制系统、反馈系统和气路系统.控制系统主要实现气路系统的送气控制和嗅剂气体浓度调节;反馈系统则负责对气体浓度进行测量;气路系统则在原有基础上添加活性炭装置,降低无关因素干扰.装置改进之后,不同气路切换时间为75.2 ms,比原装置减少了1 s,有效提高刺激精度.实验结果显示,气体浓度调节前,300 s内乙醇、吡啶、乙酸戊酯嗅剂气体浓度分别下降6.7%、71.4%、79.2%,嗅剂气体浓度短时间内发生较大改变.加入气体浓度调节功能后,当气体浓度下降至目标浓度的90%时,可通过调节气泵电压改变嗅剂气流与空气气流比例,从而调节嗅剂气体浓度至目标值,其中吡啶、乙酸戊酯用时13 s. 相似文献
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Nonlinear feedback shift registers (NFSRs) are widely used in stream cipher design as building blocks. The cascade connection of NFSRs, known as an important architecture, has been adopted in Grain family of stream ciphers. In this paper, a new sufficient condition under which an NFSR cannot be decomposed into the cascade connection of two smaller NFSRs is presented, which is easy to be verified from the algebraic normal form (ANF) of the characteristic function. In fact, our results are also applicable to nonsingular Boolean functions, which actually improve a previous research of Rhodes [6] where the characteristic functions of NFSRs cannot be contained. 相似文献
5.
《Operations Research Letters》2021,49(5):809-814
In this paper we discuss Optimal Control and Markov Decision Process (MDP) formulations of multistage optimization problems when the involved probability distributions are not known exactly, but rather are assumed to belong to specified ambiguity families. The aim of this paper is to clarify a connection between such distributionally robust approaches to multistage stochastic optimization. 相似文献
6.
《Operations Research Letters》2021,49(2):201-206
We propose Near-optimal Nonlinear Regression Trees with hyperplane splits (NNRTs) that use a polynomial prediction function in the leaf nodes, which we solve by stochastic gradient methods. On synthetic data, we show experimentally that the algorithm converges to the global optimal. We compare NNRTs, ORT-LH, Multivariate Adaptive Regression Splines (MARS), Random Forests (RF) and XGBoost on 40 real-world datasets and show that overall NNRTs have a performance edge over all other methods. 相似文献
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Laterally-coupled ridge-waveguide distributed feedback lasers fabricated without epitaxial regrowth steps have the advantages of process simplification and low cost. We present a laterally coupled grating with slots. The slots etched between the ridge and grating area are designed to suppress the lateral diffusion of carriers and to reduce the influence of the aspect-ratio-dependent-etching effect on the grating morphology in the etching process. Moreover, the grating height in this structure can be decreased to lower the aspect ratio significantly, which is advantageous over the conventional laterally coupled ridge waveguide gratings. The effects of five main structural parameters on the coupling characteristics of gratings are studied by MODE Solutions. It is found that varying the lateral width of the grating can be used as an effective way to tune the coupling strength; narrow slots (100 nm and 300 nm) and wide ridge (2 μm-4 μm) promote the stability of grating coupling coefficient and device performance. It is important to note that the grating bottom should be fabricated precisely. The comparative study of carrier distribution and mode field distribution shows that the introduction of narrow slots can strengthen the competitive advantage and stability of the fundamental mode. 相似文献
9.
Explosive synchronization in a mobile network in the presence of a positive feedback mechanism 下载免费PDF全文
Synchronization is a process that describes the coherent dynamics of a large ensemble of interacting units.The study of explosive synchronization transition attracts considerable attention.Here,I report the explosive transition within the framework of a mobile network,while each oscillator is controlled by global-order parameters of the system.Using numerical simulation,I find that the explosive synchronization(ES)transition behavior can be controlled by simply adjusting the fraction of controlled oscillators.The influences of some parameters on explosive synchronization are studied.Moreover,due to the presence of the positive feedback mechanism,I prevent the occurrence of the synchronization of continuous-phase transition and make phase transition of the system a first-order phase transition accompanied by a hysteresis loop. 相似文献
10.
为解决多属性决策单方向偏差难题所提出的灰关联投影法尚存在适用性差的技术不足。为此,在借鉴双向投影技术要点的基础上联合新型灰关联系数,并引入毕达哥拉斯犹豫模糊集的表达优势,提出基于毕达哥拉斯犹豫模糊距离测度的灰关联双向投影决策方法。新方法能够有效解决毕达哥拉斯犹豫模糊多属性决策问题,具有较高的分辨度。通过算例应用分析,直接验证了毕达哥拉斯犹豫模糊灰关联双向投影方法的实用性,间接验证了毕达哥拉斯犹豫模糊距离测度和灰关联双向投影法的有效性。 相似文献