H-infinity performance optimization for networked control systems with limited communication channels

This paper studies the problems of H-infinity performance optimization and controller design for continuous-time NCSs with both sensor-to-controller and controller-to-actuator communication constraints （limited communication channels）. By taking the derivative character of network-induced delay into full consideration and defining new Lyapunov functions, linear matrix inequalities （LMIs）-based H-infinity performance optimization and controller design are presented for NCSs with limited communication channels. If there do not exist any constraints on the communication channels, the proposed design methods are also applicable. The merit of the proposed methods lies in their Jess conservativeness, which is achieved by avoiding the utilization of bounding inequalities for cross products of vectors. The simulation results illustrate the merit and effectiveness of the proposed H-infinity controller design for NCSs with limited communication channels.

Limitations in tracking systems

In this paper, we obtain information theoretical conditions for tracking in linear time-invariant control systems. We consider the particular case where the closed loop contains a channel in the feedback loop. The mutual information rate between the feedback signal and the reference input signal is used to quantify information about the reference signal that is available for feedback. This mutual information rate must be maximized in order to improve the tracking performance. The mutual information is shown to be upper bounded by a quantity that depends on the unstable eigenvalues of the plant and on the channel capacity. If the channel capacity reaches a lower limit, the feedback signal becomes completely uncorrelated with the reference signal, rendering feedback useless. We also find a lower bound on the expected squared tracking error in terms of the entropy of a random reference signal. We show a misleading case where the mutual information rate does not predict the expected effect of nonminimum phase zeros. However, mutual information rate helps generalize the concept that there is a tradeoff when tracking and disturbance rejection are simultaneous goals, and a constraint communication channel is present in the feedback loop. Examples and simulations are provided to demonstrate some of the results.

市场空间:西部地区中小企业发展的关键

西部地区中小企业的发展对当地经济发展起决定性的作用。在目前国内市场供求基本趋于平衡、东部地区中小企业已经领先占领市场的情况下市场限制成为制约西部地区中小企业发展的主要障碍。推动西部地区中小企业的发展必须考虑我国目前的市场态势在政府大力投资下提高西部地区市场需求为以面向地区市场为主的西部中小企业提供市场空间,并抓住国家宏观经济结构调整的契机,使西部中小企业的市场进一步扩大。

THRESHOLD CONDITION FOR CHOCKING IN OPEN CHANNELS AND EXCAVATION OF TAILRACE

On the basis of energy and continuity equations a general threshold condition for chocking in open channels is obtained and a representation in terms of the Froude number at the upstream section and other parameters is given to predict whether the chocking phenomenon occurs or not at the downstream section. From the general threshold condition for chocking the limit contraction ratios of the channel width are introduced for both with and without the energy losses and a criterion for excavation of the tailrace to avoid chocking is derived. An example shows that using these criterion and the representation proposed for calculating flow depth it is very easy to determine the scheme of the excavation of the open channels.

Adaptive bit allocation scheme in multi-cell cooperative block diagonalization systems with delayed and limited feedback

In multi-cell cooperative multi-input multi-output （MIMO） systems, base station （BS） can exchange and utilize channel state information （CSI） of adjacent cell users to manage co-channel interference. Users quantize the CSIs of desired channel and interference channels using finite-rate feedback links, then BS can generate cooperative block diagonalization （BD） precoding matrices using the obtained quantized CSI at transmitter to supress co-channel interference. In this paper, a novel adaptive bit allocation scheme is proposed to minimize the rate loss due to imperfect CSI. We derive the closed-form expression of rate loss caused by both channel delay and limited feedback. Based on the derived rate loss expression, the proposed scheme can adaptively allocate more bits to quantize the better channels with smaller delays and fewer bits to worse channels with larger delays. Simulation results show that the proposed scheme yields higher performance than other allocation schemes.

（non）Markovian process quantum fisher information quantum Cramer–Rao bound decoherence channels entangled states Heisenberg＇s limit phase sensitivity

In the present study, time evolution of quantum Cramer–Rao bound of entangled N00N state, as phase sensitivity, is determined by the aid of quantum estimation theory in the presence decoherence channels. Also, the dynamic quantum process as decoherence approach is characterized by quantum fisher information flow and entanglement amount in order to distinguish between Markovian and Non-Markovian process. The comparison between quantum fisher information and quantum fisher information flow assists to comprehend the phase sensitivity evolution corresponding to Non-Markovian and Markovian process. Furthermore, as result of backflow of information from the environment to system, the phase sensitivity corresponding memory effect of environment are revived after complete decay and increase in the few times.