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Baise City, China

Chen Z.-F.,Baise University | Chen Z.-F.,Guangzhou University
Research in Astronomy and Astrophysics

We make use of the recent large sample of 17 042 Mg II absorption systems from Quider et al. to analyze the evolution of the redshift number density. Regardless of the strength of the absorption line, we find that the evolution of the redshift number density can be clearly distinguished into three different phases. In the intermediate redshift epoch (0.6 ≲ z ≲ 1.6), the evolution of the redshift number density is consistent with the non-evolution curve, however, the non-evolution curve over-predicts the values of the redshift number density in the early (z ≲ 0.6) and late (z 1.6) epochs. Based on the invariant cross-section of the absorber, the lack of evolution in the redshift number density compared to the non-evolution curve implies the galaxy number density does not evolve during the middle epoch. The flat evolution of the redshift number density tends to correspond to a shallow evolution in the galaxy merger rate during the late epoch, and the steep decrease of the redshift number density might be ascribed to the small mass of halos during the early epoch. © 2013 National Astronomical Observatories of Chinese Academy of Sciences and IOP Publishing Ltd. Source

The node localization technology of wireless sensor networks is essential and prerequisite to many applications, which it is one of the important support technologies for wireless sensor networks. The node localization is to get the position information of blind node by using location information of few known nodes and some special mechanisms. This paper primarily investigates a kind of target localization technology based on the improved DV-Hop algorithm in wireless sensor networks. We firstly compute the distances measured by RSSI and the mean value of one-hop distance. Then we can use the differences between the mean and the actual distance to get the error correction between the total distance and average one-hop distance. Replace trilateration with hybrid localization of MIN-MAX and weighted least square method. Finally, simulation experiment results show the improved algorithm can effectively carry out the network localization, thus has a certain of practical value. © 2014 ACADEMY PUBLISHER. Source

Luo C.,Baise University
WIT Transactions on Information and Communication Technologies

In real life, there exist many different kinds of transportation methods. The different method possesses its own vehicle operation cost, driving speed, and road toll rate. Therefore, the congestion toll shall be different in accordance with transportation method. This paper gives the trip time cost, operation toll cost, and the road toll cost of the general cost, based on which, combine the individual trip decision, gives the general cost of wo level programming mode based on the trip decision, and also combine the penalty function and step acceleration method to solve. © 2014 WIT Press. Source

Liu C.,Baise University | Chen W.-H.,Guangxi University
Transactions of the Institute of Measurement and Control

The guaranteed cost control problem for a class of linear uncertain discrete-time impulsive systems is considered. The parametric uncertainties are assumed to be time-varying and norm-bounded. The problem is to design a robust state feedback controller such that the resulting closed-loop system is robustly exponentially stable, and the closed-loop value of a specified quadratic cost function is not more than a certain upper bound for all admissible uncertainties and for all admissible impulse time sequences. A sufficient condition for the existence of guaranteed cost state feedback controllers is derived via a time-varying Lyapunov function approach. This condition is expressed in terms of linear matrix inequalities. Furthermore, the problem of selecting a suboptimal guaranteed cost controller is formulated as a convex optimization problem. An example is provided to demonstrate the effectiveness of the proposed results. © The Author(s) 2014. Source

Liu Z.,Guangxi University for Nationalities | Li X.,Baise University
Nonlinear Analysis: Real World Applications

In this paper, we deal with the approximate controllability for control systems described by a class of hemivariational inequalities. Firstly, we introduce the concept of mild solutions for hemivariational inequalities. Then the approximate controllability is formulated and proved by utilizing a fixed-point theorem of multivalued maps and properties of generalized Clarke subdifferential. © 2014 Elsevier Ltd. All rights reserved. Source

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