Wyniki wyszukiwania - Biblioteka Nauki

1

Recut : A Seriation Algorithm Balancing Smooth Display and Aggregated Features

100%

Qi J. , Ohsawa Y.

Fundamenta Informaticae

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2016

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tom Vol. 146, nr 3

293--304

EN

Previous seriation algorithms are confronted with a balance problem. Some approaches provide permutations with perfect wholeness, where matrix rows/columns are associated with increasing or decreasing gradient. However, this smooth permutation may lead to the blurred representation of the data structure, such as clustering structures and detailed structures inside clusters. Some other approaches indicate these structures well by tighter aggregating similar rows/columns, but this aggregation is alway at the cost of losing necessary coherence of the matrix rows/columns. In this paper, we introduce a seriation algorithm that aims at balancing the smoothness of the permutation and the clarity of the matrix structure. The permutation algorithm greedily and recursively replaces high-dissimilar object pairs with low-dissimilar ones, and the optimization algorithm searches the global optimizing solution by applying the simulated annealing algorithm. A comparison study shows both empirical and statistical evidence that Recut can provide more accurate and visually appropriate permutation by considering the balance problem.

2

Simultaneous state and parameter estimation based actuator fault detection and diagnosis for an unmanned helicopter

70%

Wu C. , Qi J. , Song D. , Qi X. , Han J.

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tom Vol. 25, no. 1

175--187

EN

Simultaneous state and parameter estimation based actuator fault detection and diagnosis (FDD) for single-rotor unmanned helicopters (UHs) is investigated in this paper. A literature review of actuator FDD for UHs is given firstly. Based on actuator healthy coefficients (AHCs), which are introduced to represent actuator faults, a combined dynamic model is established with the augmented state containing both the flight state and AHCs. Then the actuator fault detection and diagnosis problem is transformed into a general nonlinear estimation one: given control inputs and the measured flight state contaminated by measurement noises, estimate both the flight state and AHCs recursively in each time-step, which is also known as the simultaneous state and parameter estimation problem. The estimated AHCs can further be used for fault tolerant control (FTC). Based on the existing widely used nonlinear estimation methods such as the unscented Kalman filter (UKF) and the extended set-membership filter (ESMF), three kinds of adaptive schemes (KF-UKF, MIT-UKF and MIT-ESMF) are proposed by our team to improve the actuator FDD performance. A comprehensive comparative study on these different estimation methods is given in detail to illustrate their advantages and disadvantages when applied to unmanned helicopter actuator FDD.

3

Synthesis and characterization of V2O3 microcrystal particles controlled by thermodynamic parameters

61%

Qi J. , Ning G. , Zhao Y. , Tian M. , Xu Y. , Hai H.

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tom Vol. 28, No. 2

535--543

EN

A facile process is developed for the synthesis of pure vanadium(III) oxide by thermal reduction of vanadium pentoxide (V2O5) in ammonia gas. The process of thermal reduction of V2O5 was optimized by experiments and by modeling of thermodynamic parameters. The obtained V2O3 was characterized by X-ray diffraction, X-ray photoelectron spectrometry, scanning electron microscopy and thermogravimetric analysis. The experimental results indicated that crystal particles of pure V2O3 were successfully synthesized within a short reaction period of 1 h and at a relatively low temperature of 903 K. The content of V2O3 in the product sample higher than 99 wt. %. The grain size of V2O3 ranged from several hundred nanometers to several micrometers. The morphologies of the V2O3 particles were micrometer layers in nanometer sheet structure.

4

Seismic damage behaviour of aeolian sand reinforced concrete columns with I-shaped structural steel

61%

Wang Y. H. , Wang H. Y. , Wang Y. P. , Zhao M. , Qi J. , Huo G. Z. , Liu P. Q.

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2020

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tom Vol. 66, nr 4

633--650

EN

To promote the application of aeolian sand resources for steel-concrete composite structures, an aeolian sand reinforced concrete column with I-shaped structural steel is proposed in this study. Four specimens are designed and manufactured with different replacement rates of aeolian sand. The seismic behaviour and damage evolution process of the specimens are studied by low-cycle repeated loading tests. Based on the test results, the mechanical characteristics, failure modes, hysteresis curves, skeleton curves, energy dissipation capacity, displacement ductility, and stiffness degradation of the specimens with different replacement rates of aeolian sand are analysed. In addition, the effects of the design parameters on the seismic behaviour of the specimens are also studied. The results show that the indexes of the seismic behaviour can be significantly improved by adding steel. Moreover, a revised damage model is proposed, to better reflect the evolution law of seismic damage of aeolian sand reinforced concrete columns with steel. The proposed model can provide an important reference for seismic damage assessment of the columns.

5

Demonstration of a remote sensing-modelling approach for irrigation scheduling and crop growth forecasting

51%

Dabrowska-Zielinska K. , Moran M. S. , Maas S. J. , Pinter P. J. , Kimball B. A. , Mitchell T. A. , Clarke T. R. , Qi J.

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2001

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nr 05

EN

The PROtotype Biomass and Evaporation (PROBE) model was developed for simulation of daily plant growth and evaporation (E) rates in natural, vegetated ecosystems (Maas et al., 1992). The inputs to the model are basic meteorological information and periodic (weekly or bi-weekly) measurements of green leaf area index (GLAI) and E. The model uses an interactive approach with two submodels - a vegetation growth (VG) submodel and soil water balance (SWB) submodel - where the estimate of GLAI from the VG submodel is used in the SWB submodel to calculate E. In turn, the estimate of E is used in a rerun of the VG submodel to refine the estimate of GLAI. This model was tested based on meteorological data and measurements of GLAI and E acquired in a cotton (Gossypium hirsutum L.) field in central Arizona. Overall, the modelled and measured values of GLAI and E corresponded well. Results showed that the time and precision of input data were very important to obtaining accurate estimates of GLAI and E. The model showed promise for use in scheduling crop irrigations.

PL

Prototypowy model Biomasy i Ewapotranspiracji (PROBE) został utworzony do symulacji dziennego przyrostu biomasy (В) i ewapotranspiracji (E) dla naturalnych roślinnych ekosystemów (MASS et al., 1992). Danymi wejściowymi do modelu są podstawowe dane meteorologiczne i okresowe dane wskaźnika powierzchni zielonej liści (GLAT) oraz ewapotranspiracji E. Danymi wyjściowymi są codzienne wartości GLAI, E, biomasa i wilgotność gleby. Model składa się z dwóch submodeli. Pierwszy dotyczy wzrostu roślin, drugi - bilansu wodnego gleby, w którym symulowana wartość GLAI z submodelu pierwszego wpływa na obliczenie ewapotranspiracji w sub- modelu drugim. Następnie symulowana wartość E wpływa na ostateczną symulację GLAI. W wyniku pracy model został skalibrowany dla bawełny dla całego okresu wzrostu uprawy, a następnie modelowane wartości GLAI i E zostały porównane z wartościami uzyskanymi z badań terenowych. W wyniku symulacji modelu została określona dokładność wyznaczenia GLAI i E w zależności od częstotliwości, okresu i precyzji wyników GLAI i E uzyskanych teledetekcyjnie. Została zbadana przydatność tego modelu do prognozy wielkości biomasy i terminu nawodnień.