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This paper investigates the linear quadratic regulator (LQR) problem for continuous-time linear systems with redundant control inputs. The LQR control problem has been widely studied, but due to technical difficulties, there is little advance in the study of adding input redundancies. To address this problem, a convergent matrix series, the limit of a monotonically decreasing sequence, is first presented as an upper bound of the symmetric positive definite solution of a class of continuous algebraic Riccati equations (CAREs). Compared with the existing studies on this topic, the obtained bounds are more precise. Moreover, by utilising these upper bounds in the LQR problem of adding input redundancies, a class of sufficient conditions is presented to decrease the quadratic performance index. Finally, the corresponding numerical examples are given to illustrate the effectiveness of our results and compare them with the existing results. Meanwhile, some simulation experiments show that systems with redundant control inputs have good control performance. [ABSTRACT FROM AUTHOR]

The Antarctic ozone hole has attracted attention concerning global climate change. Breakthroughs regarding ozone observation methods and the formation principles of ozone holes have occurred. This study compared the slant column ozone obtained from SCanning Imaging Absorption SpectroMeter for Atmospheric CHartographY (SCIAMACHY) Level 1 optical spectroscopy data processed by QDOAS software with that reconstructed from SCIAMACHY Level 2 ozone data using geographic information to obtain the optical depth coefficients. The global distribution of optical depth coefficients reveals latitudinal homogeneity, whereas the distribution of coefficients in the polar regions reveals heterogeneity. This heterogeneity has an annual variation pattern, alternating between strong and weak distributions in the Arctic and Antarctic regions. It is most evident in the Palmer Peninsula of Antarctica, where the optical depth coefficients were significantly higher than those of the surrounding regions at the same latitude. This analysis excluded the atmospheric pressure influence and suggested the influence of the continental shelf depth. The protrusion of the continental shelf depth changes the optical depth coefficients owing to the geographical proximity of the Antarctic Palmer Peninsula to South America, which separates the Atlantic and Pacific Oceans in an east–west direction. [ABSTRACT FROM AUTHOR]

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We retrieved the absorbing aerosol index (AAI) based on the measured reflectance from the Environmental Trace Gases Monitoring Instrument (EMI) for the first time. EMI is a push-broom spectrometer onboard the Chinese GeoFen-5 satellite launched on 9 May 2018, which was initially developed to determine the global distribution of atmospheric composition. The EMI initial AAI results were corrected from physical stripes and yielded an offset of 5.92 as calibration errors from a background value based on the statistical method that count the EMI AAI over the Pacific Ocean under cloudless scenes. We also evaluated the consistency of the EMI AAI and data with the TROPOspheric Monitoring Instrument (TROPOMI) observations. A comparison between the monthly average EMI AAI data and TROPOMI AAI revealed regional consistencies between these instruments with a similar spatial distribution of AAI (correlation coefficient, r > 0.9). The daily-scale results demonstrated that EMI was also consistent with TROPOMI AAI (r = 0.9). The spatial distribution of EMI AAI is consistent with Aerosol Optical Depth (AOD) from TROPOMI. The daily variation of EMI AAI in an Australian wildfire event was consistent with TROPOMI (r = 0.92). Overall, we demonstrated that EMI AAI can be efficiently used to detect large aerosol events for reconstructing the spatial variability of Ultraviolet (UV) absorbing aerosols. [ABSTRACT FROM AUTHOR]