The strap-down inertial navigation system is a commonly used sensor for autonomous underground navigation, which can be used for shearer positioning under a coal mine. During the process of initial alignment, inaccurate or time-varying noise covariance matrices will significantly degrade the accuracy of the initial alignment of the shearer. To overcome the performance degradation of the existing initial alignment algorithm under complex underground environment, a novel adaptive filtering algorithm is proposed by the integration of the strong tracking Kalman filter and (...) the sequential filter for the initial alignment of the shearer with complex underground environment. Compared with the traditional multiple fading factor strong tracking Kalman filter method, the proposed MSTSKF algorithm integrates the advantage of strong tracking Kalman filter and sequential filter, and multiple fading factor and forgetting factor for east and north velocity measurement are designed in the algorithm, respectively, which can effectively weaken the coupling relationship between the different states and increase strong robustness against process uncertainties. The simulation and experiment results show that the proposed MSTSKF method has better initial alignment accuracy and robustness than existing strong tracking Kalman filter algorithm. (shrink)

This study uses appraisal theory to investigate the media attitudinal variations in the context of the recent 2013 air pollution incident in China. Drawing upon the appraisal systems of attitude and engagement, this article examines how the reportage has changed over time in terms of the type and source of attitude. Through a comparative analysis of the news reports and editorials in the latest and back issues of the official English-language newspaper China Daily, this article identifies two major attitudinal shifts: (...) 1) from an absence of inscribed attitude representing air quality as something natural to negative judgement of social sanction judging foreign embassies’ monitoring; 2) from judgement to three interwoven strands of appreciation, with the air quality, Western experience and prospective opportunities evaluated by both Chinese and international communities. When reporting and commenting on environmental issues of global concern, the national media voice may seek to achieve attitudinal consensus with the international community while adhering to the official discourse. (shrink)

Name der Zeitschrift: Semiotica Jahrgang: 2017 Heft: 215 Seiten: 341-364.