Finite-time adaptive sliding mode control for heavyweight airdrop operations

This paper investigates the problem of designing a fast convergent sliding mode flight controller of a transport aircraft for heavyweight airdrop operations in the presence of bounded uncertainties without the prior knowledge of the bounds. On the basis of feedback linearization of the aircraft-cargo motion system, a novel integral sliding mode flight control law with gains adaptation is proposed. It contains a nominal control law used to achieve finite-time stabilization performance and a compensated control law used to reject the uncertainties. The switching gains of the compensated control law are tuned using adaptation algorithms, and the knowledge of the bounds of the uncertainties is not required to be known in advance. Meanwhile, the severe chattering of the sliding mode control that caused by high switching gains is effectively reduced. The controller and its performance are evaluated on a transport aircraft performing a maximum load airdrop task in a number of simulation scenarios.

Application of Ethylparaben in Quality Control of Favoring Agents and Fragrances Used for Cigarette Production

This study was conducted to evaluate the antimierobial activity of ethylparaben （ethyl para-hydroxybenzoate） in flavoring agents and fragrances used tot cigarette production. In brief, different levels of ethylparaben were added to Ziyun and Ruanzhen fragrance concentrates, and fermented with or without the additiorl of extra microbial strains. The aroma components in the fermented samples were detected via gas chromatography-mass spectrometry （GC/MS） assay. The results showed that ethylparaben had good antimicrobial activity on the microorganism in Ziyun and Ruanzhen fragrances, and as it significantly inhibited the growth of Sac- charomyces sp. Aeetobacter sp. , Agrobacterium sp. and Bacillus sp. , with an inhibition rate of 53%. Under natural fermentation condition, 91. 885% of the micro- organisms were inhibited by adding 0. 1 g/kg ethylparaben, 97.69% were inhibited by adding 0.3 g/kg ethylparaben, and 100% were inhibited by adding 0.5 g/kg ethylparaben. Moreover, the addition of ethylparaben had no obvious influence on the aroma components of the favoring agents and fragrances. So, it carl be used as a preservative for the quality control of favoring agents and fragrances for cigarette production.

Causes of Deterioration and Changes of Aroma Components in Cigarette Raw Materials

The quality of the favoring agents and fragrances degenerated frequently during the storage and transportation process in a cigarette factory in Yunnan Province, causing huge economic losses. In order to ascertain the causes of deterioration, the microbial population, quantity and aroma components of the raw mate- rials were analyzed in the present study. The results showed that a total of 28 bacterial strains and one fungal strain were isolated and identified, belonging to 13 genera. The 29 strains were Bacillus sp. , Microbacterium sp. , Sphingomonas sp. , Leclercia sp. and Acinetobacter sp. isolated from normal ZY material; Bacil- lus sp. , Microbacterium sp. , Sphingomonas sp. , Brevundimonus sp. , Acinetobacter sp. , Agrobacterium sp. , Ralstonia sp. , Acetobacterium sp. , Saccharomyces sp. and Acidovorax sp. isolated from deteriorated ZY material; Agrobacterium sp. , Microbacterium sp. , Burkholderia sp. , Bacillus subtilis strain, Acetobacterium sp. and Leclercia sp. isolated from normal RZ material ; Agrobacterium sp. , Microbacterium sp. , Bacillus subtilis strain, Acetobacterium sp. , Lec/erc/a sp. , Enter- obacter sp. , Acinetobacter sp. and Saccharomyces sp. isolated from deteriorated RZ material. Microbacterium was the dominant genus by number in normal ZY ma- terial, and the population of this genus accounted for 55.6% of the total. In deteriorated ZY material, Acetobacterium, Bacillus and Saccharomyces were dominant genera, as the population of the three genera occupied 75.0% of the total. The total population of microorganisms in the deteriorated ZY material was 90 times of that in normal ZY material. In normal RZ material, the population of each of Microbacterium, Agrobacterium and Bacillus accounted for 25%, while that of each of Leclercia and Burkholderia accounted for 12.5%. In deteriorated RZ material, the population of Bacillus accounted for 65.0% of the total. The total population of the microorganisms in deteriorated RZ material was 29 times of that in normal RZ material, indicating that the deterioration of the materials was caused by microor- ganisms. The contents of aroma components were detected using two-dimensional gas chromatography-mass spectrometry （GC-MS）. The results showed that in nor- mal ZY material, the content of β-damascone was higher than that of other aroma components. And normal ZY material had higher contents of benzaldehyde, β-damascone, β-damascone, β-damascone, menthol and benzyl benzoate than deteriorated ZY material, and the differences in the contents of β-ddamascone and β-damascone were most significant between the two materials. In normal RZ material, the content of β-damascone was higher than that of other aroma components. And normal RZ material had higher contents of menthol, ethyl capratc, β-damascone, β-damascone and tabanane C than deteriorated RZ material, and the differ- ences in the contents of ethyl caprate and capric acid were most significant between the two materials. The results revealed that aroma components changed greatly in deteriorated tobacco materials.

Output feedback adaptive DSC for nonlinear systems with guaranteed L-infinity tracking performance

In this paper, the problem of output tracking for a class of uncertain nonlinear systems is considered. First, neural networks are employed to cope with uncertain nonlinear functions, based on which state estimation is constructed. Then, an output feedback control system is designed by using dynamic surface control （DSC）. To guarantee the L-infinity tracking performance, an initialization technique is presented. The main feature of the scheme is that explosion of complex- ity problem in backstepping control is avoided, and there is no need to update the unknown parameters including control gains as well as neural networks weights, the adaptive law with one update parameter is necessary only at the first design step. It is proved that all signals of the closed-loop system are semiglobally uniformly ultimately bounded and the L-infinity performance of system tracking error can be guaranteed. Simulation results demonstrate the effectiveness of the proposed scheme.