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Wyświetlanie 1-10 z 10
Tytuł:
Fabrication of High-Density GaN Nanowires through Ammoniating $Ga_2O_3//Nb$ Films
Autorzy:
Zhuang, H.
Li, B.
Zhang, S.
Zhang, X.
Xue, Ch.
Wang, D.
Shen, J.
Powiązania:
https://bibliotekanauki.pl/articles/1813498.pdf
Data publikacji:
2008-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
68.65.-k
81.05.Ea
81.15.Cd
Opis:
High-density GaN nanowires were successfully synthesized on Si(111) substrates through ammoniating $Ga_2O_3//Nb$ films under flowing ammonia atmosphere at 950°C. The as-synthesized GaN nanowires are characterized by X-ray diffraction, selected-area-electron diffraction, Fourier transform infrared, scanning electron microscopy, and field-emission transmission electron microscopy. The results show that the synthesized nanowires are single-crystal hexagonal wurtzite GaN with diameters ranging from 30 to 100 nm and lengths up to several microns. The photoluminescence spectra measured at room temperature only exhibit a strong and broad emission peak at 367.8 nm. Finally, the growth mechanism of GaN nanowires is discussed.
Źródło:
Acta Physica Polonica A; 2008, 113, 2; 723-730
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optimum design of fiber angle and hole orientation of an orthotropic plate
Autorzy:
Zhang, X.
Lu, A.
Wang, S.
Zhang, N.
Powiązania:
https://bibliotekanauki.pl/articles/280011.pdf
Data publikacji:
2018
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
orthotropic plate
fiber orientation angle
hole orientation angle
conformal transformation method
differential evolution algorithm
Opis:
With the goal of decreasing the stress concentration along the hole boundary in an orthotropic plate under inequi-biaxial loadings, an optimum design of the fiber angle and hole orientation is presented. The maximum absolute tangential stress along the hole boundary is taken as the objective function, and the fiber orientation angle and the hole orientation angle are considered as design variables. The conformal transformation method of a complex function and the Differential Evolution (DE) algorithm are used. Two non-circular shapes, ellipse and hexagon are taken as examples to analyze the problem. Based on the results, we can conclude that the major axis of elliptical holes should be designed in the direction of the maximum external loading for a perforated structure in an orthotropic plate. However, the principal direction that has the larger Young’s modulus should be inclined to the direction of the minimum loading, especially for a significantly orthotropic plate.
Źródło:
Journal of Theoretical and Applied Mechanics; 2018, 56, 1; 297-311
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Functional traits related to environmental divergence in combination with phylogenetic relationship of Picea species
Autorzy:
Wang, M.
Wang, J.
Zhang, A.
Zhang, X.
Sun, S.
Zhao, C.
Powiązania:
https://bibliotekanauki.pl/articles/2077949.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Instytut Dendrologii PAN
Tematy:
δ13C
P50
Picea
seeva
quantitative convergence index
Opis:
Background: Plants have adapted to fine-scale environmental heterogeneity through ecologically important traits, leading to new lineages. This suggests that differentiation of important traits has been beneficial to habitat partitioning among closely related species. However, the pattern of ecological divergences and differentiation of functional traits in combination with phylogenetic relationships have not been widely examined. Material and methods: To illustrate the pattern of ecological divergences of nine Picea species, spatial evolutionary and ecological vicariance analysis (seeva) was used to quantify and test the divergence between sister lineages. Five functional traits were measured in a common garden experiment. For all traits the quantitative convergence index (QVI) was determined. Furthermore, their relationships with divergent environmental variables were analyzed in the context of phylogenetic relationships. Results: Temperature variables (maximum temperature of warmest month and temperature annual range) split at basal nodes and precipitation variables (annual precipitation and precipitation of driest quarter) split at terminal nodes. Conservative traits were leaf mass per area (LMA) and net photosynthetic rate (Pn), which reflected selective retention when ancestors suffered cold environmental separation. Meanwhile, linear stomatal density (LSD), carbon-13 isotope ratio (δ13C) and water potential at 50% loss of hydraulic conductivity (P50) were convergent between species, but only P50 exhibited adaption to different precipitation conditions. The nine Picea species exhibit a distinct environmental divergence pattern. LMA and Pn were selectively retained when their ancestors were subjected to cold environmental separation. P50 was an important trait with respect to adaptation to precipitation differences. This research provided a new way of expounding the correlation between environment, functional traits and phylogeny, deepening our understanding of environmental divergence, trait differentiation and speciation.
Źródło:
Dendrobiology; 2018, 80; 131-142
1641-1307
Pojawia się w:
Dendrobiology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Antibiotic resistance and molecular characteristics of Staphylococcus aureus isolated from pigs in Hunan, China
Autorzy:
Zhang, X.
Wang, G.
Yin, C.
Powiązania:
https://bibliotekanauki.pl/articles/2087249.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
antibiotic resistance
molecular characterization
pig-associated S. aureus
Hunan
Źródło:
Polish Journal of Veterinary Sciences; 2020, 23, 4; 563-570
1505-1773
Pojawia się w:
Polish Journal of Veterinary Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A novel fibre Bragg grating curvature sensor for structure deformation monitoring
Autorzy:
Liu, M.-Y.
Zhou, S.-G.
Song, H.
Zhou, W.-J.
Zhang, X.
Powiązania:
https://bibliotekanauki.pl/articles/221816.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
fibre Bragg grating
curvature sensor
large structure parts
deformation monitoring
Opis:
Real-time monitoring of deformation of large structure parts is of great significance and the deformation of such structure parts is often accompanied with the change of curvature. The curvature can be obtained by measuring changes of strain, surface curve and modal displacement of the structure. However, many factors are faced with difficulty in measurement and low sensitivity at a small deformation level. In order to measure curvature in an effective way, a novel fibre Bragg grating (FBG) curvature sensor is proposed, which aims at removing the deficiencies of traditional methods in low precision and narrow adjusting. The sensor combines two FBGs with a specific structure of stainless steel elastomer. The elastomer can transfer the strain of the structure part to the FBG and then the FBG measures the strain to obtain the curvature. The performed simulation and experiment show that the sensor can effectively amplify the strain to the FBG through the unique structure of the elastomer, and the accuracy of the sensor used in the experiment is increased by 14% compared with that of the FBG used for direct measurement.
Źródło:
Metrology and Measurement Systems; 2018, 25, 3; 577-587
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Real-time optical demultiplexing with the chirped pulses
Autorzy:
Li, Y.
Zhang, X.
Yuan, J.
Kang, Z.
Sang, X.
Kang, S.
Kang, X.
Yan, B.
Wang, K.
Yu, C.
Powiązania:
https://bibliotekanauki.pl/articles/175106.pdf
Data publikacji:
2018
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
linearly chirped pulse
parametric process
real-time optical demultiplexing
Opis:
A scheme for real-time optical demultiplexing is proposed by utilizing the time-broadened and linearly chirped pulses instead of the conventional mode-locked pulses. The copies of the optical-time-division-multiplexed signal are acquired through a dual-pump parametric gate and used as the parametric multicast block. Simulation results show that the demultiplexing from 160 Gb/s down to sixteen 10 Gb/s tributaries can be achieved only by using a sampling source of 10 GHz. The proposed scheme can effectively reduce the complexity of parallel processing, and find important applications in the high-speed all-optical signal processing.
Źródło:
Optica Applicata; 2018, 48, 4; 621-632
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Reconstruction algorithm for obtaining the bending deformation of the base of heavy-duty machine tool using inverse Finite Element Method
Autorzy:
Liu, M.
Zhang, X.
Song, H.
Wang, J.
Zhou, S.
Powiązania:
https://bibliotekanauki.pl/articles/221566.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
inverse Finite Element Method
bending deformation
heavy-duty machine tool
reconstruction algorithm
statically indeterminate structure
Opis:
The field of mechanical manufacturing is becoming more and more demanding on machining accuracy. It is essential to monitor and compensate the deformation of structural parts of a heavy-duty machine tool. The deformation of the base of a heavy-duty machine tool is an important factor that affects machining accuracy. The base is statically indeterminate and complex in load. It is difficult to reconstruct deformation by traditional methods. A reconstruction algorithm for determining bending deformation of the base of a heavy-duty machine tool using inverse Finite Element Method (iFEM) is presented. The base is equivalent to a multi-span beam which is divided into beam elements with support points as nodes. The deflection polynomial order of each element is analysed. According to the boundary conditions, the deformation compatibility conditions and the strain data measured by Fiber Bragg Grating (FBG), the deflection polynomial coefficients of a beam element are determined. Using the coordinate transformation, the deflection equation of the base is obtained. Both numerical verification and experiment were carried out. The deflection obtained by the reconstruction algorithm using iFEM and the actual deflection measured by laser displacement sensors were compared. The accuracy of the reconstruction algorithm is verified.
Źródło:
Metrology and Measurement Systems; 2018, 25, 4; 727-741
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A quadrature-free Legendre polynomial approach for the fast modelling guided circumferential wave in anisotropic fractional order viscoelastic hollow cylinders
Autorzy:
Zhang, X.
Liang, S.
Shao, S.
Yu, J.
Powiązania:
https://bibliotekanauki.pl/articles/38615994.pdf
Data publikacji:
2021
Wydawca:
Instytut Podstawowych Problemów Techniki PAN
Tematy:
guided wave
fractional order derivative
anisotropic viscoelastic hollow cylinder
quadrature-free Legendre polynomial approach
dispersion
attenuation
Opis:
Compared to the traditional integer order viscoelastic model, a fractional order derivative viscoelastic model is shown to be advantageous. The characteristics of guided circumferential waves in an anisotropic fractional order Kelvin–Voigt viscoelastic hollow cylinder are investigated by a quadrature-free Legendre polynomial approach combining the Weyl definition of fractional order derivatives. The presented approach can obtain dispersion solutions in a stable manner from an eigenvalue/eigenvector problem for the calculation of wavenumbers and displacement profiles of viscoelastic guided wave, which avoids a lot of numerical integration calculation in a traditional polynomial method and greatly improves the computational efficiency. Comparisons with the related studies are conducted to validate the correctness of the presented approach. The full three dimensional spectrum of an anisotropic fractional Kelvin–Voigt hollow cylinder is plotted. The influence of fractional order and material parameters on the phase velocity dispersion and attenuation curves of guided circumferential wave is discussed in detail. Moreover, the difference of the phase velocity dispersion and attenuation characteristics between the Kelvin–Voigt and hysteretic viscoelastic models is also illustrated. The presented approach along with the observed wave features should be particularly useful in non-destructive evaluations using waves in viscoelastic waveguides.
Źródło:
Archives of Mechanics; 2021, 73, 2; 121-152
0373-2029
Pojawia się w:
Archives of Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A new troodontid theropod from the Late Cretaceous of central China, and the radiation of Asian troodontids
Autorzy:
Lu, J
Xu, L.
Liu, Y.
Zhang, X.
Jia, S.
Ji, Q.
Powiązania:
https://bibliotekanauki.pl/articles/20912.pdf
Data publikacji:
2010
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
new theropod
Late Cretaceous
Central China
Asian troodontid
troodontid
Theropoda
Troodontidae
Xixiasaurus
Cretaceous
Henan province
China
paleontology
Opis:
A new troodontid dinosaur, Xixiasaurus henanensis gen. et sp. nov., from the Upper Cretaceous Majiacun Formation of the Xixia Basin, Henan Province, is erected, based on a partial skull. It is characterized by bearing 22 maxillary teeth, a distinct opening on the lateral surface of the base of nasal process of the premaxilla, the rostral end of the upper jaw forming a tapered U−shape, and the mandibular symphyseal region slightly inflected medially. Xixiasaurus is most closely related to the Mongolian Byronosaurus among troodontids. Byronosaurus, Urbacodon, and Xixiasaurus may form a new clade, suggesting an endemic radiation of troodontids across Asia, including multiple taxa without dental serrations. The discovery of Xixiasaurus in the Xixia Basin may imply that the Xixiasaurus−bearing Majiacun Formation is Campanian in age.
Źródło:
Acta Palaeontologica Polonica; 2010, 55, 3; 381-388
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Preparation and Properties of Natural Cellulose Fibres from
Otrzymywanie i właściwości folii celulozowych z włókien łykowych
Autorzy:
Qu, L
Tian, M.
Guo, X.
Pan, N
Zhang, X.
Zhu, S
Powiązania:
https://bibliotekanauki.pl/articles/234492.pdf
Data publikacji:
2014
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Biopolimerów i Włókien Chemicznych
Tematy:
Broussonetia papyrifera (BP)
natural cellulose fibre
fibre extraction
microwave-assisted
włókna celulozowe
włókna łykowe
folia celulozowa
Broussonetia Papyrifera (BP)
Opis:
Natural cellulose fibres from Broussonetia papyrifera (L.) Vent. (BP) bast were systematically investigated in this paper. To begin with, BP fibres were successively extracted from BP bast by four different degumming methods, among which the microwave-assisted method exhibited high efficiency. It was found that non-cellulose substances were sufficiently removed or reduced after the degumming process, but the cellulose I structure had not changed from bast to fibres based on the XRD and FTIR results. Meanwhile the BP fibres exhibited high crystallinity (75 ~ 77%), high breaking strength (2.19 ~ 2.39 cN/dtex) and a remarkable moisture region (6.3 ~ 8.7%), but low breaking elongation (1.0 ~ 2.1%). All those results indicated that the BP fibres had properties resembling those of traditional natural cellulose fibres (e.g. cotton and flax); therefore they could be viewed as a promising alternative source for natural cellulose bundle fibres.
Artykuł poświecono systematycznym badaniom naturalnych włókien celulozowych z Broussonetia Papyrifera (BP). Włókna ekstrahowano z włókien łykowych BP poprzez 4 rożne metody odpreparowania pomiędzy z których metoda za pomocą zastosowania ultradźwięków pozwoliła na uzyskanie wysokiej wydajności. Stwierdzono, że nie celulozowe substancje były dostatecznie usunięte lub zredukowane po procesie odpreparowania. Dzięki badaniom XRD i FITR można było wykazać, że struktura celulozy (I) nie zmieniła się pomiędzy włóknami łykowymi i otrzymanymi z nich wyrobami. dalsze badania wykazały źe włókna BP maja wysoką krystaliczność (75 - 77%), wysoką wytrzymałość(2.19 - 2.39 cN/dtex) i znaczną pochłanialność wilgoci (6.3 - 8.7%) natomiast małe wydłużenie przy zerwaniu (1.0 - 2.1%). Wszystkie te wyniki wskazują,że włókna BP posiadają właściwości przypominające właściwości tradycyjnych, naturalnych włókien celulozowych (np. bawełny i lnu). Dlatego też badane włok-na można uważać jako alternatywne źródło naturalnych włókien celulozowych.
Źródło:
Fibres & Textiles in Eastern Europe; 2014, 4 (106); 24-28
1230-3666
2300-7354
Pojawia się w:
Fibres & Textiles in Eastern Europe
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-10 z 10

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