Li Shuai

This paper focuses on the problem of target tracking using k fittest robots in a group of n mobile robots with n>k. We present centralized and distributed coordination models with all-to-all and limited communications, respectively. For the case of all-to-all communication between robots, theoretical analysis is presented to prove the exponential stability of the whole system. In real applications of robotic networks, a robot may only be allowed to exchange information with a limited number of neighbors. In such a limited communication case where centralized quantity is not available, a consensus filter is used to estimate the centralized quantities in a distributed way, and a distributed competitive target tracking is thus achieved. The stability of the distributed control is also proved in theory. Finally, illustrative examples are provided and analyzed to substantiate the efficacy of the proposed models for tracking moving target in a competition manner with all-to-all communications and limited communications.

This study examined the ability to comprehend conventional and non-conventional implicatures, and the effect of proficiency and learning context on comprehension of implicature in L2 Chinese. Participants were three groups of college students of Chinese: elementary-level foreign language learners, advanced-level foreign language learners, and advanced-level heritage learners. They completed a 36-item computer-delivered listening test measuring their ability to comprehend three types of implicature: conventional indirect refusals, conventional indirect opinions, and non-conventional indirect opinions. Comprehension was analyzed for accuracy and comprehension speed. There was a significant effect of implicature type on accuracy, but not on comprehension speed. A significant effect of participant group was observed on accuracy, but the effect was mixed on comprehension speed.

In this paper, a seven-parameter BRDF model with double-peak characteristic, which could fit double-peak data, was adopted to fit the BRDF of Mars simulation soil. At the same time, the three-dimensional figure of the original data of the sample and the three-dimensional curve of the fitted curve were given. The results proved that the model worked well for this type of data. In addition, the experimental data of four kinds of earth sand samples with different roughness were also fitted and analyzed. It was found that the model still had a good fitting effect on such data. At last, the Mars simulation soil and the four kinds of earth sand samples with different roughness were compared horizontally and vertically. Moreover, the double-peak characteristics and other properties of the Mars simulation soil and the earth sand were analyzed under the same and different roughness.