Wyniki wyszukiwania - Biblioteka Nauki

1

Discrete Sliding Mode Control for DC-DC Converters with Uncertainties

100%

Yan M. , Fan L.

Przegląd Elektrotechniczny

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2012

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tom R. 88, nr 5b

60-63

EN

A discrete-time sliding mode controller is presented for DC-DC converters. A criterion for the existence of the sliding surface is derived based on the LMI technique combined with the Lyapunov method. In addition, the design of sliding mode control is presented according to the reachability condition. The control law can effectively constrain the input disturbance and reduce the effects from the parameter variations while the bounds of the uncertainties are unknown. Finally, simulation results show the feasibility and effectiveness of the proposed method.

PL

Zaprezentowano kontroler ślizgowy o czasie dyskretnym do przekształtników DC-DC. Kryterium obecności powierzchni ślizgowej jest wyprowadzone bazując na technice LMI i metodzie Lapunowa.

2

Coupling analysis of connectivity between coarse sediment source areas and deposition area in the Yellow River, China

100%

He L. , Yan M.

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nr 2

EN

As a coupling river system, watershed management in sediment source areas may influence downstream reach. However, the connectivity between water and sediment retention (WSR) in two coarse sediment source areas (tributaries entering the Inner Mongolia Reach, IMR, and tributaries entering the Middle Yellow River, MYR) and deposition in the Lower Yellow River (LYR) have rarely been compared. Experiential fitted models for each river segment (IMR, MYR, and LYR) are loosely linked to investigate the coupling relationship between source areas and deposition area. Analysis shows that, at the zonal scale, the connectivity between WSR in different zones and deposition reduction in different river reaches differs. WSR in tributaries of the IMR may benefit the local channel (IMR) with a priority ratio, and WSR in the stem channel of the IMR may benefit both the local (IMR) and the lower (LYR) channels with almost the same magnitude. WSR in the MYR may benefit the local channel (LT reach) and the lower channel (LYR), while the LYR has more propriety. At the zonal scale, the temporal scales over which changes in hillslopes occur also differ, as WSR in the IMY and MYR during the non-flood season may also contribute to deposition reduction in the MYR and LYR. In total, the loosely linked model may provide information of sediment along the whole river network.

3

Evaluation on gas supply reliability of urban gas pipeline network

80%

Li J. , Yan M. , Yu J.

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tom Vol. 20, no. 3

471--477

EN

As one of the lifeline projects, an urban gas network is a complex system, as it requires maintenance of the supply capacity when any single pipeline is isolated due to failure. For such a system, its reliability needs to be evaluated. Considering that existing structural reliability and hydraulic reliability analyses reflect different aspects of the working conditions of an urban gas network, system reliability theory is employed to explain that only the gas supply reliability can achieve a comprehensive evaluation of the work capacity of the entire urban gas network, as it takes into account the combined influence of the structural reliability and hydraulic reliability. To calculate the parameters in the gas supply reliability evaluation, such as pipeline failure rate, flow reduction in the gas network under different failure conditions, etc., some research achievements in the field of structural reliability and hydraulic reliability are fully utilized. Then, the detailed calculation procedures of these parameters are given to evaluate the gas supply reliability in terms of operational and practical considerations. Finally, using an example of a simple double-loop gas network, the detailed process of the gas supply reliability evaluation of an urban gas network is described, and the feasibility of this evaluation method is also illustrated.

PL

Miejska sieć gazowa – jeden z kluczowych elementów infrastruktury miasta – stanowi złożony system, ponieważ wymaga utrzymania zdolności przesyłowej gdy przepływ gazu w jednym z rurociągów zostaje zamknięty w wyniku awarii. W przypadku tego rodzaju systemów, konieczna jest ocena niezawodności. Biorąc pod uwagę, iż dostępne w literaturze analizy niezawodności konstrukcyjnej i niezawodności hydraulicznej odzwierciedlają różne aspekty warunków pracy miejskiej sieci gazowej, nie dają one pełnego obrazu niezawodności systemu jako całości. W artykule wykorzystano teorię niezawodności systemów, która pokazuje, że jedynie ocena niezawodności dostaw gazu stanowić może kompleksową ocenę wydajności pracy całej miejskiej sieci gazowej, ponieważ uwzględnia ona zarówno wpływ niezawodności konstrukcji jak i niezawodności hydraulicznej sieci. W pracy wykorzystano dotychczasowe obserwacje badawcze dotyczące oceny niezawodności konstrukcyjnej i niezawodności hydraulicznej sieci gazowej do obliczenia parametrów oceny niezawodności dostaw gazu, takich jak intensywność uszkodzeń rurociągu, redukcja przepływu gazu w sieci gazowej w różnych warunkach uszkodzeń, itp. Następnie, podano szczegółowe procedury obliczania tych parametrów w celu oceny niezawodności przesyłowej sieci gazowej pod kątem eksploatacyjnym i praktycznym. Na koniec, na przykładzie prostej sieci gazowej składającej się z dwóch pętli, opisano szczegółowy proces oceny niezawodności dostaw gazu w miejskiej sieci gazowej i zilustrowano możliwość wykorzystania proponowanej metody.

4

Effects of ten traditional Chinese herbs on immune response and disease resistance of Sciaenops ocellatus (Actinopterygii: Perciformes: Sciaenidae)

80%

Pan T. , Yan M. , Chen S. , Wang X.

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nr 1

EN

Background. Traditional Chinese herbs (TCHs) are widely used for improving non-specific immunity of fish in aquaculture. Possible effects of many important TCH on red drum, Sciaenops ocellatus (Linnaeus, 1766), have not been adequately studied. The aim of the presently reported study was to investigate the effects of ten TCH on selected immunological- and haematological responses of red drum. Materials and Methods. >Ten TCH preparations, consisting of selected parts of plants and fungi, known in medicinal practice as: Astragalus membranaceus, fructus forsythiae, Polyporus umbellatus, Scutellaria baicalensis, Wolfiporia extensa, rhizoma coptidis, radix glycyrrhizae, flos lonicerae japonicae, isatidis radix, and bupleuri radix were used in the experiment. A dose of 10 g of each TCH was decocted and concentrated, then mixed with the diets (mixed diets) at ratio of 2%. After 28 days of feeding, the fish were infected with Vibrio splendidus and observed for 14 days for possible mortalities. Leukocyte phagocytic activity and lysozyme activity (LZM) were measured on days 0, 3, 7, 14, 21, 28, and 35. Relative percentage survival (RPS) of each TCH treatment was also investigated after the fish exposure to V. splendidus. Results. Red drum fed 2% doses of individual TCH extracts significantly (P < 0.05) increased its: phagocytic percentage (PP) (with the exception of flos lonicerae japonicae treatment), phagocytic index (PI) (with the exception of flos lonicerae japonicae- and bupleuri radix treatments), LZM (with the exception of Wolfiporia extensa treatment), and RPS (with the exception of P. umbellatus, Wolfiporia extensa-, radix glycyrrhizae-, flos lonicerae japonicae-, isatidis radix-, and bupleuri radix treatments). The indexes of PP, PI, and LZM, for all experimental groups, decreased quickly on day 35 (7 days after TCH diets were discontinued). On the other hand, PP values were significantly (P < 0.05) higher than in control (with the exception of flos lonicerae japonicae- and Wolfiporia extensa treatments). Also PI values were significantly higher (P < 0.05) than in control (with the exception of flos lonicerae japonicae-, Wolfiporia extensa-, and bupleuri radix treatments). LZM values exhibited no significant difference (P > 0.05) in all treatment groups compared with control. Most importantly, the A. membranaceus-, or S. baicalensis-, or fructus forsythiae-fed groups were significantly protected (P < 0.01) against V. splendidus challenge compared to control. RPS of A. membranaceus- and S. baicalensis groups were the highest, reaching 88.9% on day 28, followed by the fructus forsythiae group, whereas bupleuri radix- and Wolfiporia extensa treatments showed the lowest values. Conclusion. A. membranaceus, S. baicalensis, and fructus forsythiae were effective in preventing red drum from acquiring the disease while challenged by V. splendidus.