Wyniki wyszukiwania - Biblioteka Nauki

1

Duals of homogeneous weighted sequence Besov spaces and applications

100%

Huang P.-K. , Wang K.

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tom Vol. 17, nr 2

181-205

EN

In this article, we study the duals of homogeneous weighted sequence Besov spaces b α,q p,w, where the weight w is non-negative and locally integrable. In particular, when 0 < p < 1, we find a type of new sequence spaces which characterize the duals of b α,q p,w. Also, we find the necessary and sufficient conditions for the boundedness of diagonal matrices acting on homogeneous weighted sequence Besov spaces. Using these results, we give some applications to characterize the boundedness of Fourier-Haar multipliers and paraproduct operators. In this situation, we need to require that the weight w is an Ap weight.

2

A Curvature-Tensor-Based Perceptual Quality Metric for 3D Triangular Meshes

80%

Torkhani F. , Wang K. , Chassery J. M.

Machine Graphics and Vision

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2014

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tom Vol. 23, No. 1/2

59--82

EN

Perceptual quality assessment of 3D triangular meshes is crucial for a variety of applications. In this paper, we present a new objective metric for assessing the visual difference between a reference triangular mesh and its distorted version produced by lossy operations, such as noise addition, simplification, compression and watermarking. The proposed metric is based on the measurement of the distance between curvature tensors of the two meshes under comparison. Our algorithm uses not only tensor eigenvalues (i.e., curvature amplitudes) but also tensor eigenvectors (i.e., principal curvature directions) to derive a perceptually-oriented tensor distance. The proposed metric also accounts for the visual masking effect of the human visual system, through a roughness-based weighting of the local tensor distance. A final score that reflects the visual difference between two meshes is obtained via a Minkowski pooling of the weighted local tensor distances over the mesh surface. We validate the performance of our algorithm on four subjectively-rated visual mesh quality databases, and compare the proposed method with state-of-the-art objective metrics. Experimental results show that our approach achieves high correlation between objective scores and subjective assessments.

3

Biodiversity Versus stability: the biological effect of plant functional traits on ecosystem functioning in grasslands dominated by Leymus chinensis

80%

Zhao N. , Shao X. , Wang K.

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tom 64

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nr 3

EN

Although diversity-ecosystem theory predicts that ecosystem functioning is strongly determined by species number, species traits play an important role in regulating ecosystem-level dynamics. We analyze responses of species attributes to diversity level and resource availability, and explore their consequences for ecosystem functioning and ultimately assess the contributions of five traits (vegetative plant height, clonal growth, root depth, cespitose habit and seed mass) to ecosystem functioning defined by spatial stability of community biomass. We found that functional traits disproportionately affected spatial stability. Relationships between species functional traits and spatial stability of community biomass indicated that diversity of vegetative plant height facilitated stability of a nitrogen fertilized undisturbed natural community (NAT), and that of a phosphorus fertilized forb, legume and bunchgrass community (FLB). The clonal growth form was also identified as a stabilizing trigger for a unfertilized undisturbed natural community (NAT), whereas diversity in root depth, cespitose habit and seed mass were related to destabilization of a nitrogen fertilized rhizomatous grass community (RRR). Studies quantifying interactions among plant traits, community structure and ecological functioning will contribute much more to understanding of the effects of the ecological behavior of specific traits on the ecosystem functioning.

4

Soil organic carbon, aggregates, and fractions under different land uses in the Loess Plateau, China

80%

Qu Z. , Jiang R. , Wang K. , Li M.

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nr 3

EN

The dynamics of soil organic carbon (SOC) under different land uses can be beneficial for accurately assessing carbon sequestration to deal with global climate change. The aim of this study was to quantify the SOC content in various fractions under different land uses. Soil samples were collected from the top 0.1 m and 0.1-0.3 m of cropland, grassland, and forest in Huachi County of Gansu Province, China. Significant differences in physical fractions were found in the top 0.1-m layer, with cropland having the highest proportion of micro-aggregates (<250 μm), forest having the highest proportion of small macro-aggregates (250-2000 μm), and grassland tending to form large macro-aggregates (>2000 μm). SOC values were 6.9, 11.3, and 10.3 g kg⁻¹ in the top 0.1-m layer for cropland, grassland, and forest, respectively. The difference in δ¹³C between the light and heavy fraction in small macro-aggregates was smaller than that in both large macro-aggregates and micro-aggregates. These results indicated that small macro-aggregates conserved SOC relative to micro-aggregates and large macro-aggregates. The differences in δ¹³C between the light and heavy fraction in all aggregate size fractions of grassland were much larger than in forest, indicating that there was higher microbial decomposition in grasslands. Overall, our results suggested that the accumulation of SOC in grassland was derived from the abundant carbon input, but the protection of SOC from small macro-aggregates was important to forest soil.

5

Method of regularized sources for two-dimensional Stokes flow problems based on rational or exponential blobs

71%

Wen S. , Wang K. , Zahoor R. , Li M. , Šarler B.

Computer Assisted Methods in Engineering and Science

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2015

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tom Vol. 22, no. 3

289--300

EN

The solution of Stokes flow problems with Dirichlet and Neumann boundary conditions is performed by a non-singular method of fundamental solutions (MFS) which does not require artificial boundary, i.e., source points of fundamental solution coincide with the collocation points on the boundary. The fundamental solution of the Stokes pressure and velocity is obtained from the analytical solution due to the action of the Dirac delta- type force. Instead of Dirac delta force, a non-singular function called blob, with a free parameter epsilon is employed, which is limited to Dirac delta function when epsilon is limited to zero. The analytical expressions for related Stokes flow pressure and velocity around such regularized sources have been derived for rational and exponential blobs in an ordered way. The solution of the problem is sought as a linear combination of the fields due to the regularized sources that coincide with the boundary and with their intensities chosen in such a way that the solution complies with the boundary conditions. A numerical example for two-dimensional (2D) driven cavity and a flow between parallel plates are chosen to assess the properties of the method. The results of the posed method of regularized sources (MRS have been compared with the results obtained by the fine-grid second-order classical finite difference method (FDM) and analytical solution. The results converge with finer discretisation; however, they depend on the value of epsilon. The method gives reasonably accurate results for the range of epsilon between 0.1 and 0.5 of the typical nodal distance on the boundary. Exponential blobs give slightly better results than the rational blobs; however, they require slightly more computing time. A robust and efficient strategy to find the optimal value of epsilon is needed in the perspective.

6

Effects of elevated CO2 and temperature on growth and morphology of fir (Abies faxoniana, Rehd. e t Wils.) and native herbs in a treeline ecotone: an experimental approach

71%

Hou Y. , Luo Z. , Jenerette G. D. , Qiao Y. , Wang K.

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nr 2

EN

Determining how changes in atmospheric CO₂ concentrations and climate affects growth of species is helpful for understanding plant community species shift in response to future environmental changes. In the present study, fir (Abies faxoniana) and native herbs from treeline ecotone of east Qinghai-Tibetan Plateau (altitude: 3230–3300 m) were exposed to ambient CO₂ or ambient +350 μmol·mol⁻¹ CO₂ concentration in combination with ambient or ambient +2°C air temperature for two years in enclosedtop chambers. The results showed that elevated CO₂ , elevated temperature and the combination of elevated CO₂ and temperature increased biomass, height and diameter of fir compared to the control. Elevated CO₂ decreased biomass of Deyeuxia scabrescens, but increased for Fragaria orientalis and Cardamine tangutorum. Except for Fragaria orientalis, herbaceous biomass decreased by elevated temperature. The combination stimulated growth of Fragaria orientalis and Cardamine tangutorum, but suppressed for Deyeuxia scabrescens and Carex kansuensis. The results also demonstrated that elevated CO₂ and temperature increased the crown size and altered the morphology of fir, with benefits for resource capture, and did not affect growth of herbs. Larger root to shoot ratio of fir contributed the enhancement of biomass, while negatively influencing the growth of some herbs. This indicates morphological changes of trees may modify their growth responses and species around them to environmental changes. The different effects of elevated CO₂ and temperature on the growth of species in treeline ecotone suggest that climate change may alter community composition and structure.

7

A New Hybrid Feature Extraction Method for Partial Discharge Signals Classification

71%

Liao R. , Wang K. , Yang L. , Duan L. , Li J.

Przegląd Elektrotechniczny

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2012

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tom R. 88, nr 11a

191-195

EN

In this paper, a new hybrid feature extraction method combining adaptive optimal radially Gaussian kernel (AORGK) time-frequency representation with two dimensional nonnegative matrix factorization (2DNMF) is proposed for partial discharge (PD) classification. Firstly, AORGK is applied to obtain the time-frequency matrices of PD ultra-high-frequency (UHF) signals. Then 2DNMF is employed to compress the AORGK amplitude (AORGKA) matrices to extract various feature vectors with different (d1, d2) combinations, i.e. (5, 5), (5, 10), (10, 5) and (10, 10). Finally, the extracted features are classified by fuzzy k nearest neighbor (FkNN) classifier and back propagation neural network (BPNN). 600 samples sam pled from four typical artificial defect models in Laboratory are adopting for testing of the proposed feature extraction algorithm. It is shown that the successful rate by FkNN and BPNN are all higher than 80%, and FkNN has superior classification accuracies than BPNN under four circumstances of (d1, d2) combinations. In addition, FkNN achieves the highest classification accuracy 93.73% with (10, 5) combination. The results demonstrate that it is feasible to apply the proposed algorithm to PD signal classification.

PL

W artykule przedstawiono nową hybrydową metodę klasyfikacji wyładowań niezupełnych (ang. Partial Discharge), wykorzystującą algorytm AORGK (ang. Adaptive Optimal Radially-Gaussian Kernel) o nieujemnej, matrycowej faktoryzacji dwuwymiarowej (ang. 2-Dimensional Nonnegative Matrix Factorization). W metodzie wykorzystano także algorytm k najbliższych sąsiadów oparty na teorii zbiorów rozmytych (ang. Fuzzy k Nearest Neighbour Classifier) oraz sieci neuronowe (ang. Back Propagation Neural Network).

8

DC-Link Voltage Balancing Method with Reduced CommonMode Voltage for a Five-Level ANPC Inverter

71%

Wang K. , Li Y. , Zheng Z. , Xu L. , Feng J.

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tom R. 89, nr 3b

32--34

EN

This paper presents a DC-link voltage balancing method with reduced common-mode voltage for a five-level active neutral-point clamped (ANPC) inverter. The DC-link voltage balancing method is based on zero-sequence voltage injection using carrier-based PWM. By further limiting the range of injected zero-sequence voltages, the amplitude of common-mode voltage can be reduced to 1/4 of the dc-link voltage. Experimental results are presented to verify the validity of this method.

PL

W artykule przedstawiono metodę balansowania napięciami kondensatorów obwodu pośredniczącego DC dla pięcio-poziomowego falownika Active NPC z redukcją napięcia common-mode. W metodzie wykorzystywana jest modulacja PWM z falą nośną i sygnałem kolejności zerowej, o regulowanym zakresie aplikacji. Przedstawiono wyniki eksperymentalne.

9

Nonlinear motion law of coalbed gas seepage under the combined effects of stress field and temperature field

71%

Li B. , Wei J. , Li P. , Wang K. , Borisyuk Y. A.

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tom Vol. 94, nr 2

106--113

EN

The shrinkage and swelling of the coal matrix due to the effects of temperature were investigated through the performance by Henan Province Key Lab of Gas Geology & Gas Control of a permeability test of loaded coal under various temperature and working conditions using its own seepage equipment for thermo-fluid-solid-mechanical coupling of methane-containing coal. The variation of coal permeability under the combined effects of stress and temperature was investigated, and the gas motion law in the coal samples was tested. The variation equations of coal permeability under the combined effects of stress and temperature, as well as the motion equations describing the nonlinear gas seepage law in coal seams were established. The established equations were proved to fit well with the experimental data, which demonstrated that the motion equations and the research methods were both reasonable. Study on the seepage nonlinear motion law of gas in the coal seam is great significance to mineral gas extraction.

10

Effect of core temperature on the oxidation of lipids and proteins during steam cooking of large-mouth bass (Micropterus salmoides)

61%

Wang K. , Bao Y. , Yang H. , Wang Y. , Chen D. , Regenstein J. M. , Zhou P.

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nr 3

11

Serological surveillance of avian influenza virus and canine distemper virus in captive Siberian Tigers in Northeastern China

61%

Wang K. , Wang H. , Feng N. , Zhao Y. , Gao Y. , Hu G. , Xia X.

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nr 3

12

Construction of a recombinant baculovirus expressing swine hepatitis E Virus ORF2 and preliminary research on its immune effect

51%

Yang Z. , Wang K. , Hu Y. , Yuan P. , Yang Y. , Xie L. Y. , Huang S. L. , Liu J. , Ran L. , Song Z. H.

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13

RhNAC31, a novel rose NAC transcription factor, enhances tolerance to multiple abiotic stresses in Arabidopsis

51%

Ding A. , Li S. , Li W. , Hao Q. , Wan X. , Wang K. , Liu Q. , Liu Q. , Jiang X.

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nr 06

EN

Plant-specific NAM, ATAF1/2, and CUC (NAC) transcription factors serve essential functions in plant development and plant responses to environmental cues. Yet, transcription factors specific to the rose (Rosa hybrida) NAM/CUC3 subfamily are poorly understood. Here, we identify a novel NAM/CUC3-subfamily transcription factor, RhNAC31, that is associated with flower opening and can be induced by increased salt, cold, and dehydration stress treatment. RhNAC31 has a transactivation region in its C-terminal region, and its overexpression is associated with enhanced cold tolerance in Arabidopsis, conferring a higher survival rate and reduced reactive oxygen (H₂O₂ and O₂⁻) levels. Under salt stress conditions, plants overexpressing RhNAC31 displayed increased germination rates and lower levels of H₂O₂, malondiadehyde (MDA), peroxidase (POD), and superoxide dismutase (SOD). Moreover, RhNAC31 conferred enhanced drought resistance by reducing the rate of water loss through leaves. Further characterization revealed a higher sensitivity of RhNAC31 transgenic plants to abscisic acid (ABA) both during and post-germination, causing lower germination and root inhibition rates under ABA treatment. Quantitative PCR experiments showed that numerous abiotic stress-related genes were activated by RhNAC31 overexpression. Our results highlight RhNAC31 as a positive transcriptional regulator of tolerance to multiple abiotic pressures, and we conclude that RhNAC31 has potential for use in the molecular breeding of stress-tolerant crops.

14

The endogenous ligand for guanylate cyclase-C activation reliefs intestinal inflammation in the DSS colitis model

51%

Lan D. , Wen Y. , Dong X. , Yang Q. , Liu Y. , Wang K. , Li H. , Miao Y.

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nr 3

15

Cause analysis of soft and hard rock tunnel collapse and information management

51%

Li L. , Wang Q. , Li S. , Huang H. , Shi S. , Wang K. , Lei T. , Chen D.

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nr 4

EN

Collapse is very common in tunnel construction, which can bring immense casualties and economic losses. The interface of soft and hard rock is the typical location for a tunnel collapse. During Shimenya Tunnel construction, collapse of the section ZK123+370~ZK123+365 of the left tunnel occurred. This paper discusses how distribution of layered rock, attitude of the stratum, hydrogeololgy, and advanced geological prediction can contribute to tunnel collapse. According to collapse mechanisms and in situ collapse conditions, managing and monitoring plans were applied to the tunnel collapse section. To ensure the efficiency and safety of collapse management, convergence displacement and arch crown settlement were measured in the process of tunnel information management. Cause analysis of soft and hard rock tunnel collapse and information management can provide a beneficial reference for avoiding tunnel collapse and developing collapse management programs.

16

Effect of growth time on the morphologies of vapour grown carbon fibres and a suggested mechanism of growth

51%

Zhang H. , Shi J. , Song Y. , Zhao J. , Wang K. , Guo Q. , Zhai G. , Liu L.

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tom Vol. 27, No. 3

885--890

EN

The microstructure of vapour grown carbon fibres is two-double layered. This paper addresses the question of morphology transformation of vapour grown carbon fibres. Special attention is given to developing understanding of the growth mechanism of the outer layer of the fibres. The influence of growth time on the morphologies of as-prepared carbon fibres was investigated using scanning electron microscopy. Results showed that with the prolongation of reaction time, their morphology changed from linear fibres to carbon micro-bead chains and then again to thicker linear fibres, which led to the increase of the carbon fibres diameters from 200 nm to several micrometers. Furthermore, several kinds of carbon fibres with special morphology such as carbon micro-beads, chains, etc., could be obtained by adjusting the growth time. A growth mechanism, henceforth referred to as fibre-bead-thicker fibre, for the outer layer of vapour grown carbon fibres is proposed.