Controllability Analysis and Degraded Control for a Class of Hexacopters Subject to Rotor Failures

This paper considers the controllability analysis and fault tolerant control problem for a class of hexacopters. It is shown that the considered hexacopter is uncontrollable when one rotor fails, even though the hexacopter is over-actuated and its controllability matrix is row full rank. According to this, a fault tolerant control strategy is proposed to control a degraded system, where the yaw states of the considered hexacopter are ignored. Theoretical analysis indicates that the degraded system is controllable if and only if the maximum lift of each rotor is greater than a certain value. The simulation and experiment results on a prototype hexacopter show the feasibility of our controllability analysis and degraded control strategy.Comment: 21 pages, 7 figures, submitted to Journal of Intelligent & Robotic System

Antiviral Therapy and Outcomes of Patients with Pneumonia Caused by Influenza A Pandemic (H1N1) Virus

There is limited data on the clinical outcome of patients with pandemic H1N1 (pH1N1) pneumonia who received oseltamivir treatment, especially when the treatment was administered more than 48 hours after symptom onset.During the pandemic in 2009, a cohort of pH1N1 influenza pneumonia was built in China, and their clinical information was collected systematically, and analyzed with Cox models.<200, oseltamivir administration reduced the mortality risk by 92.1%, 88% and 83.5%, respectively. Higher doses of oseltamivir (>3.8 mg/kg/d) did not improve clinical outcome (mortality, higher dose 2.5% vs standard dose 2.8%, p>0.05).<200

Environmental change in Jiaozhou Bay recorded by nutrient components in sediments

Inorganic or bulk organic chemical indicators, including organic carbon (OC), total nitrogen, organic nitrogen (ON), fixed ammonium (N-fix), exchangeable ammonium, exchangeable nitrate, organic phosphorus (OP), inorganic phosphorus (IP), and biogenic silica (BSi), were examined in a 3-m core collected in Jiaozhou Bay (JZB) to decipher how the environment has changed during the preceding two centuries of increasing anthropogenic influence in this region. Concentrations of BSi, OC, and OP reveal overall increases to ca.30 cm (similar to 1984), then decreased toward the surface, probably reflecting a decrease in the productivity of overlying waters since 1984. Aquaculture might play an important role in the decrease of nutrient elements in the upper layers recorded in sediments. The decreased molar BSi/OC ratios upcore may be due to a change in dominance from large- to small-sized diatoms, as shown in other research. However, the shift may also be related to changes from heavily-silicified to lightly-silicified diatoms or to non-siliceous forms such as dinoflagellates. ON concentrations increased towards the surface sediment, which is most likely consistent with the increase in fertilizer application and wastewater discharge. Concentrations of IP, total P. and Nfix all decreased conspicuously upcore at 41 cm depth (similar to 1977), and were largely consistent with the decrease in rainfall and freshwater discharge to JZB. Our data suggest that the environment has significantly changed since the 1980s. Anthropogenic activities in the watersheds may exert a substantial influence on carbon cycling processes in estuaries and potentially the coastal ocean. (C) 2010 Elsevier Ltd. All rights reserved

Ordered distributed nickel sulfide nanoparticles across graphite nanosheets for efficient oxygen evolution reaction electrocatalyst

Low-cost and earth-abundant nickel chalcogenides with versatilities in electrocatalysis, conversion and storage of energy are hindered in practical application due to the low electrical conductivity and small specific surface area. In the present work, we report a simple preparation of 2D nanocomposites of NiSx (5 nm) uniformly embedded in several layered graphite (NiSx@graphite) through the sulfidation of nickel naphtalenedicarboxylic acid framework nanosheets (∼9 nm). The obtained NiSx@graphite nanosheet composites are used for oxygen evolution reaction (OER) catalysis. Electrochemical studies reveal that their OER activities under strongly alkaline conditions are ranked in the order of Ni9S8@graphite > NiS@graphite > NiS2@graphite. The outstanding OER performance offered by Ni9S8@graphite owes to the synergistic effects of large specific surface area and the special structure between nickel sulfide and graphite layer, and the intrinsic large TOFs and the optimal adsorption energy of Ni9S8. Furthermore, Ni9S8@graphite as an anode material used for lithium ion batteries (LIBs) also shows a high specific capacity with competitive rate performance. Such excellent performance and low price render nickel chalcogenides a promising candidate for the future OER catalyst and LIBs application.Ministry of Education (MOE)This work was financially supported by the China Scholarship Council (201706280166), the National Natural Science Foundation of China (grant numbers 51472198, 51772237, 51777152), Singapore MOE Tier 1 (grant number M4011959), the Fundamental Research Funds for the Central Universities (grant number XJJ2016020), the Scientific Research Foundation for the Returned Overseas Chinese Scholars