Wyniki wyszukiwania - Biblioteka Nauki

1

Determination of the calcium sulfate hemihydrate content by regression analysis using the initial setting time

100%

Li B.

Archives of Civil Engineering

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2020

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tom Vol. 66, nr 2

421--437

EN

In this paper, we randomly select 75 sets data of calcium sulfate hemihydrate (CSH) content and initial setting time, and the traditional test method of CSH and analyses initial setting time was used by complexometric titration. So the close relationship between them was studied in depth, which classification fitting data to be analyzed by regression analysis. The result shows that this regression analysis method can accurately determine CSH content in modified industrial by-product gypsum. The determination method has the advantages of simplification and rapid operation. As well as, the XRF quantitative analytical method was used to test the CSH content, which verified the accuracy of regression analysis method. The results also show that this method has high accuracy, and can simplify the traditional experimental process. The method developed is easier and more convenient and has broad prospects in application.

2

Anti-periodic solutions for Clifford-valued high-order Hopfield neural networks with state-dependent and leakage delays

51%

Huo N. , Li B. , Li Y.

International Journal of Applied Mathematics and Computer Science

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2020

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tom Vol. 30, no. 1

83--98

EN

A class of Clifford-valued high-order Hopfield neural networks (HHNNs) with state-dependent and leakage delays is considered. First, by using a continuation theorem of coincidence degree theory and the Wirtinger inequality, we obtain the existence of anti-periodic solutions of the networks considered. Then, by using the proof by contradiction, we obtain the global exponential stability of the anti-periodic solutions. Finally, two numerical examples are given to illustrate the feasibility of our results.

3

Effects of plastic film mulching on soil nematodes and soil quality at different growth stages of maize planted in semiarid areas of China

51%

Li B. , Wang Y. , Li X. , Liu B.

Polish Journal of Ecology

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2022

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tom Vol. 70, nr 2-3

103--116

EN

Plastic mulching is considered as a simple, yet effective land management measure to modify microclimate in semi-arid areas. However, the influence of plastic mulching on local soil nematodes and soil quality needs to be investigated more deeply. To fill the knowledge gap, we compared the characteristics of soil nematode communities (density, trophic structure), soil enzyme activities, soil physicochemical properties, and their relationships between maize fields cultivated with use of plastic film mulching and no film mulching, under the same land conditions in Chifeng region, Inner Mongolia. The results showed that the total number of nematodes in most of the film mulched (FM) fields was lower than in no film mulched (nFM) fields. Most of soil chemical properties showed no significant difference between nFM samples and FM samples. Only 0–10 cm soil layer in nFM samples had significantly higher urease activity than in FM samples in June. Plastic film mulching may have an adverse effect on soil quality. Thus, the correct and effective use of plastic film mulch is one of the important measures for future agricultural development in semiarid areas.

4

Research on the Performance Optimization of Turbulent Self-Noise Suppression and Sound Transmission of Acoustic Windows Made from Functionally Graded Material

45%

Li B. , Zhou F.-L. , Fan J. , Wang B. , Tan L.

Archives of Acoustics

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2023

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tom Vol. 48, No. 4

475--495

EN

For a simplified sonar dome model, an optimization method for internal gradients of functionally graded material (FGM) acoustic windows is proposed in this paper. This method can be used to design optimized FGM acoustic windows with better turbulent self-noise suppression and sound transmission performances. A theoretical model of FGM acoustic windows to evaluate the reduction of self-noise caused by the turbulent boundary layer (TBL) pulsating pressure and the sound transmission loss (STL) is derived through the double Fourier transform and the wavenumber frequency spectrum analysis, respectively, based on the transfer matrix idea and the classical elastic theory. The accuracy of the theory is verified by the finite element results of COMSOL Multiphysics. Utilizing the genetic algorithm (GA) and taking the monotonic gradient as the constraint condition, the internal gradient optimization method of FGM acoustic windows obtains the optimization variables in the Bernstein polynomial when the optimization objective is minimized by iterating the optimization variables in the deviation function represented by the Bernstein polynomial that is introduced in the gradient function. The STL, the turbulent self-noise reduction or a weighting function of the STL and turbulent self-noise reduction of FGM acoustic windows is chosen as the optimization objective. The optimization calculation of the sound transmission or turbulent self-noise suppression performances is carried out for the FRP-rubber FGM (FGM with fiber reinforced plastic (FRP) as the substrate material and rubber as the top material) acoustic window. The optimized results show that both the sound transmission and turbulent self-noise suppression performance are effectively improved, which verifies the effectiveness of the optimization method. Finally, the mechanism of the sound transmission and self-noise suppression characteristics before and after optimization are explained and analyzed based on the equivalent model of graded materials. The research results of this paper provide a reference value for the future design of FGM acoustic windows for sonar domes.