The output feedback control for uncertain nonholonomic systems

This paper considers the problems of almost asymptotic stabilization and global asymptotic regulation （GAR） by output feedback for a class of uncertain nonholonomic systems. By combining the nonsmooth change of coordinates and output feedback domination design together, we construct a simple linear time-varying output feedback controller, which can universally stabilize a whole family of uncertain nonholonomic systems. The simulation demonstrates the effectiveness of the proposed controller.

具有学习和推理能力的空间无人系统智能架构

以卫星、飞船、深空探测器为代表的航天器是一类典型的无人系统,经历了从自动化到自主化的不断发展.为提升航天器对未知空间环境和复杂空间任务的适应能力和智能自主水平,以空间无人系统为研究对象设计了具有学习和推理能力的无人系统智能架构,给出架构的组成及功能;接着分析该架构中学习和推理能力的运作机制,并针对架构所需的动作库和知识库的构建、更新与扩展方法等关键技术提出解决方案;最后通过地外星表巡视采样任务示例,具体说明在该智能架构下的新知识生成、基于知识的推理和自主执行任务的过程,以及过程中知识库、环境、任务和动作库之间的交互关系.

On the boundedness of running-in attractors based on recurrence plot and recurrence qualification analysis

A feature parameter was proposed to quantitatively explore the boundedness of running-in attractors;its variation throughout the friction process was also investigated. The enclosing radius R was built with recurrence plots(RPs) and recurrence qualification analysis(RQA) by using the time delay embedding and phase space reconstruction. Additionally, the typology of RPs and the recurrence rate(RR) were investigated to verify the applicability of R in characterizing the friction process. Results showed that R is larger at the beginning, but exhibits a downward trend in the running-in friction process;R becomes smooth and trends to small steady values during the steady-state friction period, and finally shows an upward trend until failure occurs. The evolution of R, which corresponded with the typology of RPs and RR during friction process, can be used to quantitatively analyze the variation of the running-in attractors and friction state identifacation. Hence, R is a valid parameter, and the boundedness of running-in attractors can offer a new way for monitoring the friction state of tribological pairs.

Dehydrogenation of Isobutane to Isobutene with Carbon Dioxide over SBA-15-Supported Chromia-Ceria Catalysts

A series of SBA-15-supported chromia-ceria catalysts with 3% Cr and 1%--5% Ce （3Cr-Ce/SBA） were pre- pared using an incipient wetness impregnation method. The catalysts were characterized by XRD, N2 adsorption, SEM, TEM-EDX, Raman spectroscopy, UV-vis spectroscopy, XPS and H2-TPR, and their catalytic performance for isobutane dehydrogenation with CO2 was tested. The addition of ceria to SBA-15-supported chromia improves the dispersion of chromium species. 3Cr-Ce/SBA catalysts are more active than SBA-15-supported chromia （3Cr/SBA）, which is due to a higher concentration of Cr^6＋ species present on the former catalysts. The 3Cr-3Ce/SBA catalyst shows the highest activity, which gives 35.4% isobutane conversion and 89.6% isobutene selectivity at 570℃ after 10 min of the reaction.

ADAPTIVE PRACTICAL OUTPUT MANEUVERING CONTROL FOR A CLASS OF NONLINEAR SYSTEMS

This paper deals with the adaptive practical output maneuvering control problems for a class of nonlinear systems with uncontrollable unstable linearization. The objective is to design a smooth adaptive maneuvering controller to solve the geometric and dynamic tasks with an arbitrary small steady tracking error. The method of adding a power integrator and the robust recursive design technique are employed to force the system output to track a desired path and make the tracking speed to follow a desired speed along the path. An example is considered and simulation results are given. The proposed design procedure can be illustrated by the use of this example.

Isobutane Dehydrogenation Assisted by C02 over Silicalite-i-Supported ZnO Catalysts: Influence of Support Crystallite Size

The ZnO catalysts supported on Silicalite-1 zeolites with different crystallite sizes(0.08,0.35,1 and 1.7 jjm,respectively)and 5%Zn were synthesized via an incipient wetness method.The catalysts were characterized by XRD,N2 adsorption,SEM,TEM-EDX,DRIFT spectra and NH3-TPD,and their catalytic performance in isobutane dehydrogenation assisted by C02 was investigated.The catalytic activity is strongly dependent on the crystallite size of Silicalite-1 support.The ZnO/S-l-O.35 catalyst with ca.0.35 μmcrystallite size displays the highest activity,affording an initial isobutane conversion of 51.0%and 74.5%isobutene selectivity.This can be attributed to a higher amount of acid sites present on this catalyst as well as the largest amount of nest silanols possessed by the S-l-0.35 support.

Drag derived altitude aided navigation method

The navigation problem of the lifting reentry vehicles has attracted much research interest in the past decade. This paper researches the navigation in the blackout zone during the reentry phase of the aircraft, when the communication signals are attenuated and even interrupted by the blackout zone. However, when calculating altitude, a pure classic inertial navigation algorithm appears imprecise and divergent. In order to obtain a more precise aircraft altitude, this paper applies an integrated navigation method based on inertial navigation algorithms, which uses drag derived altitude to aid the inertial navigation during the blackout zone. This method can overcome the shortcomings of the inertial navigation system and improve the navigation accuracy. To further improve the navigation accuracy, the applicable condition and the main error factors, such as the atmospheric coefficient error and drag coefficient error are analyzed in detail. Then the damping circuit design of the navigation control system and the damping coefficients determination is introduced. The feasibility of the method is verified by the typical reentry trajectory simulation, and the influence of the iterative times on the accuracy is analyzed. Simulation results show that iterative three times achieves the best effect.

Single Exposure to Cocaine Impairs Reinforcement Learning by Potentiating the Activity of Neurons in the Direct Striatal Pathway in Mice

Plasticity in the glutamatergic synapses on striatal medium spiny neurons(MSNs)is not only essential for behavioral adaptation but also extremely vulnerable to drugs of abuse.Modulation on these synapses by even a single exposure to an addictive drug may interfere with the plasticity required by behavioral learning and thus produce impairment.In the present work,we found that the negative reinforcement learning,escaping mild foot-shocks by correct nose-poking,was impaired by a single in vivo exposure to 20 mg/kg cocaine 24 h before the learning in mice.Either a single exposure to cocaine or reinforcement learning potentiates the glutamatergic synapses on MSNs expressing the striatal dopamine 1(D1)receptor(D1-MSNs).However,24 h after the cocaine exposure,the potentiation required for reinforcement learning was disrupted.Specific manipulation of the activity of striatal D1-MSNs in D1-cre mice demonstrated that activation of these MSNs impaired reinforcement learning in normal D1-cre mice,but inhibition of these neurons reversed the reinforcement learning impairment induced by cocaine.The results suggest that cocaine potentiates the activity of direct pathway neurons in the dorsomedial striatum and this potentiation might disrupt the potentiation produced during and required for reinforcement learning.