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Tytuł:
Study of flow softening mechanisms of a nickel-based superalloy with o phase
Autorzy:
Lin, Y. C.
He, D.-G
Chen, M. S.
Chen, X.-M.
Zhao, C.-Y.
Ma, X.
Powiązania:
https://bibliotekanauki.pl/articles/958203.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
alloys
hot deformation
flow softening behavior
microstructural evolution
Opis:
The flow softening behaviors of a nickel-based superalloy with o phase are investigated by hot compression tests over wide ranges of deformation temperature and strain rate. Electron backscattered diffraction (EBSD). optical microscopy (OM), and scanning electron microscopy (SEM) are employed to study the flow softening mechanisms of the studied superalloy. It is found that the flow softening behaviors of the studied superalloy are sensitive to deformation temperature and strain rate. At high strain rate and low deformation temperature, the obvious flow softening behaviors occur. With the increase of deformation temperature or decrease of strain rate, the flow softening degree becomes weaken. At high strain rate (1s-1), the flow softening is mostly induced by the plastic deformation heating and flow localization. However, at low strain rate domains (0.001-0.01s-1), the effects of deformation heating on flow softening are slight. Moreover, the flow softening at low strain rates is mainly induced by the discontinuous dynamic recrystallization and the dissolution of 6 phase (Ni3Nb).
Źródło:
Archives of Metallurgy and Materials; 2016, 61, 3; 1537-1546
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Particle swarm optimization based fuzzy clustering approach to identify optimal number of clusters
Autorzy:
Chen, M.
Ludwig, S. A.
Powiązania:
https://bibliotekanauki.pl/articles/91549.pdf
Data publikacji:
2014
Wydawca:
Społeczna Akademia Nauk w Łodzi. Polskie Towarzystwo Sieci Neuronowych
Tematy:
optimization
fuzzy clustering
cluster analysis
particle swarm optimization (PSO)
PSO
fuzzy Sammon mapping
Sammon mapping
Opis:
Fuzzy clustering is a popular unsupervised learning method that is used in cluster analysis. Fuzzy clustering allows a data point to belong to two or more clusters. Fuzzy c-means is the most well-known method that is applied to cluster analysis, however, the shortcoming is that the number of clusters need to be predefined. This paper proposes a clustering approach based on Particle Swarm Optimization (PSO). This PSO approach determines the optimal number of clusters automatically with the help of a threshold vector. The algorithm first randomly partitions the data set within a preset number of clusters, and then uses a reconstruction criterion to evaluate the performance of the clustering results. The experiments conducted demonstrate that the proposed algorithm automatically finds the optimal number of clusters. Furthermore, to visualize the results principal component analysis projection, conventional Sammon mapping, and fuzzy Sammon mapping were used.
Źródło:
Journal of Artificial Intelligence and Soft Computing Research; 2014, 4, 1; 43-56
2083-2567
2449-6499
Pojawia się w:
Journal of Artificial Intelligence and Soft Computing Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Engineering example of the constraint forces in non-holonomic mechanical: forklift-truck robot motion. Part I
Autorzy:
Haddout, S.
Guennoun, M. A.
Chen, Z.
Powiązania:
https://bibliotekanauki.pl/articles/230034.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
forklift-truck robot
Lagrangian systems
nonholonomic constraints
reduced equations of motion
numerical solution
Opis:
In the presented paper, a problem of nonholonomic constrained mechanical systems is treated. New methods in nonholonomic mechanics are applied to a problem of a Forklift-truck robot motion. This method of the geometrical theory of general nonholonomic constrained systems on fibered manifolds and their jet prolongations, based on so-called Chetaev-type constraint forces. The relevance of this theory for general types of nonholonomic constraints, not only linear or affine ones, was then verified on appropriate models. On the other hand, the equations of motion of a Forklift-truck robot are highly nonlinear and rolling without slipping condition can only be expressed by nonholonomic constraint equations. In this paper, the geometrical theory is applied to the above mentioned mechanical problem. The results of numerical solutions of constrained equations of motion, derived within the theory, are presented.
Źródło:
Archives of Control Sciences; 2018, 28, 3; 483-506
1230-2384
Pojawia się w:
Archives of Control Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Comparative investigations of nonlinear and linear observers for a highly manoeuvrable target in sliding mode guidance
Autorzy:
Wang, Y.
Sun, M.
Du, S.
Chen, Z.
Powiązania:
https://bibliotekanauki.pl/articles/201020.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
guidance law
second-order sliding mode
super-twisting algorithm
linear observer
target manoeuvre
algorytm
obserwator liniowy
manewr
algorytm przesuwania
Opis:
Target manoeuvre is one of the key factors affecting guidance accuracy. To intercept highly maneuverable targets, a second-order sliding-mode guidance law, which is based on the super-twisting algorithm, is designed without depending on any information about the target motion. In the designed guidance system, the target estimator plays an essential role. Besides the existing higher-order sliding-mode observer (HOSMO), a first-order linear observer (FOLO) is also proposed to estimate the target manoeuvre, and this is the major contribution of this paper. The closed-loop guidance system can be guaranteed to be uniformly ultimately bounded (UUB) in the presence of the FOLO. The comparative simulations are carried out to investigate the overall performance resulting from these two categories of observers. The results show that the guidance law with the proposed linear observer can achieve better comprehensive criteria for the amplitude of normalised acceleration and elevator deflection requirements. The reasons for the different levels of performance of these two observer-based methods are thoroughly investigated.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2017, 65, 2; 233-245
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On the Interaction of Resonance And Bragg Scattering Effects for the Locally Resonant Phononic Crystal with Alternating Elastic and Fluid Matrices
Autorzy:
Yuan, B.
Chen, Y.
Jiang, M.
Tang, S.
He, M.
Tu, M.
Powiązania:
https://bibliotekanauki.pl/articles/177103.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
locally resonant phononic crystals
effective speed of sound
coupling band gaps
underwater acoustic materials
Opis:
Three-dimensional (3D) locally resonant phononic crystals (LRPCs) are studied with the aim of optimising the sub-wavelength band gaps of such composites. By analysing their effective acoustic properties, it has been found that the effective acoustic speed of the composite will drop to zero when local resonance arise, and will increase monotonically when Bragg scattering effects occur. Moreover, if the matrix is a low-shear-speed medium, local resonators can significantly reduce the effective acoustic speed of the composite and, therefore, lower the frequency where Bragg scattering effects occur. Hence, a specific LRPC with alternating elastic and fluid matrices is proposed, whose resonance and Bragg gaps are already close in frequency. The fluid matrix behaves as a wave filter, which prevents the shear waves from propagating in the composite. By using the layer-multiple-scattering theory, the coupling behaviour of local resonance and Bragg scattering band gaps has been investigated. Both gaps are enhanced when they move closer to each other. Finally, a gap-coupled case is obtained that displays a broad sub-wavelength band gap. Such proposal excels at the application of underwater acoustic materials since the arrangement of structure can be handily adjusted for tuning the frequency of coupled gap.
Źródło:
Archives of Acoustics; 2017, 42, 4; 725-733
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An enclosed dust removal system with ducting
Zamknięty system odpylania z kanalizacją
Autorzy:
Xie, J.
Xue, S.
Chen, W. M.
Zhou, G.
Powiązania:
https://bibliotekanauki.pl/articles/348688.pdf
Data publikacji:
2012
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
chodnik
pyły
modelowanie numeryczne
zamknięty system odpylania
roadways
dusts
enclosed dust removal system
numerical modeling
Opis:
A numerical modeling study is undertaken to understand gas-solid particle flows at the face of a mechanically developing roadway of an underground coal mine which employs a force-exhaust auxiliary ventilation system and uses mist spray for dust suppression. The FLUENT, a commercial computational fluid dynamics (CFD) package is used with Semi Implicit Method for Pressure Linked Equations (SIMPLE) algorithm for simulation. The results of the modeling show that dust control should focus on the middle area of the face. Based on the results, an enclosed dust removal system with ducting was developed. The system was successfully trialed at an underground coal mine with a satisfactory result.
Aby uzyskać przebieg przepływu cząstek gazu na przodku mechanicznie kształtowanego chodnika przewozowego w kopalni podziemnej wykorzystującej system wentylacji kombinowanej i system natrysku rozpylającego do tłumienia pylenia przeprowadzono badania z wykorzystaniem modeli numerycznych. Dla celów symulacji użyto pakietu FLUENT - ogólnodostępnego systemu pomiaru dynamiki płynów w połączeniu z algorytmem SIMPLE. Wyniki modelu pokazują, że odpylanie winno koncentrować się na środkowej powierzchni przodka. Na podstawie uzyskanych wyników opracowano zamknięty system odpylania z kanalizacją. System przetestowano w kopalni z zadowalającym efektem.
Źródło:
AGH Journal of Mining and Geoengineering; 2012, 36, 3; 423-433
1732-6702
Pojawia się w:
AGH Journal of Mining and Geoengineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
“Noise” in climatologically driven ocean models with different grid resolution
Autorzy:
Tang, S.
von Storch, H.
Chen, X.
Zhang, M.
Powiązania:
https://bibliotekanauki.pl/articles/48986.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Instytut Oceanologii PAN
Tematy:
climate system
noise
nonlinear model
high-dimensional nonlinear model
macroturbulence
spatial distribution
daily variation
South China Sea
Źródło:
Oceanologia; 2019, 61, 3
0078-3234
Pojawia się w:
Oceanologia
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Surfactant assisted removal of engine oil from synthetic soil
Autorzy:
Ramamurthy, A. S.
Chen, Z.
Li, X.
Azmal, M.
Powiązania:
https://bibliotekanauki.pl/articles/207953.pdf
Data publikacji:
2015
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
sodium dodecyl sulfate
SDS
desorption
polyethylene oxides
sodium
sodium sulfate
soils
surface active agents
dodecylosiarczan sodu
surfaktanty anionowe
desorpcja
tlenki polietylenu
sód
siarczan sodowy
gleba
środki powierzchniowo czynne
detergenty
Opis:
Effectiveness of surfactants SDS (sodium dodecyl sulfate), AOT (sodium dioctyl sulfosuccinate) and Brij 35 (polyoxyethylene lauryl ether) in removing residual oil from soils have been determined. Experimental results indicated that oil desorption efficiencies with surfactants are 7 to 18 times higher than using water alone. 0.6% Brij 35 at was the most effective surfactant to remove oil from soil, and it did not display any significant change in oil desorption with pH changes. A comparison study also showed that pore volume was a more significant parameter than soil washing flow rate to improve oil desorption.
Źródło:
Environment Protection Engineering; 2015, 41, 2; 67-79
0324-8828
Pojawia się w:
Environment Protection Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Biomechanical evaluation of tendon connection with novel suture techniques
Autorzy:
Chen, Z.
Wang, J.
Wei, J.- S.
Hou, Z.-Y.
Li, M.
Chen, Q.-X
Powiązania:
https://bibliotekanauki.pl/articles/306902.pdf
Data publikacji:
2018
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
ścięgno Achillesa
IFLL
biomechanika
internal fixation with limited loop
Achilles tendon
biomechanics
Opis:
Achilles tendon rupture is a severe injury with poor curative effect due to its anatomical characteristic and mechanical peculiarity. Internal fixation of limited loop (IFLL) with steel-wire has been applied on patients with tendon rupture to fix the broken ends before physical rehabilitation. The purpose of this study is to investigate the biomechanical property and radiological characteristic of such suture technique for the repairment of tendon rupture. Methods: Tendons of pigs’ hint feet were separated for the biomechanical study. Suture surgery was performed according to the protocol of IFLL. Biomechanical Testing Machine was adopted to conduct the biomechanical tensile load examination. The maximal load, elastic modulus and tendon stiffness of the stitched tendons with or without reinforcement were examined. Results: The maximum tensile load of the stitched tendons using IFLL reached 1/4 of the uninjured tendon’s maximum tensile load, indicating that such suture technique is capable of providing enough tension for the ruptured tendon. Surprisingly, tendons fixed with titanium wire showed the highest load tension, which was comparable to the undamaged tendon. Therefore, we found the biomechanical basis of using IFLL in effectively connecting the rupture ends of tendons. Conclusions: In conclusion, we provide biomechanical evidence for the use of IFLL in treatment of Achilles tendon rupture, by providing enough strength for the ankle function. Such suture technique could help the patients with better rehabilitation and reduced in-hospital stay after Achilles tendon injury.
Źródło:
Acta of Bioengineering and Biomechanics; 2018, 20, 1; 135-141
1509-409X
2450-6303
Pojawia się w:
Acta of Bioengineering and Biomechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Leaching of heavy metals from MSWI fly ash : experiments vs. simulation
Autorzy:
Qiu, Q
Jiang, X.
Chen, Z.
Lu, S.
Ni, M.
Powiązania:
https://bibliotekanauki.pl/articles/205253.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
simulation
MSWI fly ash
microwave
hydrothermal treatment
Visual MINTEQ
Opis:
In this work, pH-dependence experiments and leaching modeling using Visual MINTEQ were performed to evaluate the stability and simulate the leaching characteristics of heavy metals in municipal solid waste incineration (MSWI) fly ash. Modeling the equilibrium concentration of Cd, Cu, Cr, Ni, Pb and Zn in raw and treated fly ash was the main target and was conducted over a pH range of 0.5–14. In addition, simulation of the leaching behavior of MSWI fly ash with different additives was also conducted. The treated fly ash was solidified by a microwave-assisted hydrothermal process with added phosphate. The initial elemental concentrations of MSWI fly ash, including raw and treated fly ash, were detected by a microwave apparatus and inductively coupled plasma atomic emission spectroscopy (ICP-AES). The ICP-AES analysis showed that most leaching concentrations of treated fly ash decreased considerably compared to the raw fly ash. The simulation results indicated that the dissolution/precipitation simulation models of Zn, Cu and Pb were broadly consistent with the experimental results, while the leaching behaviors of Ni, Cr and Cd were determined by both dissolution/precipitation and surface complexation mechanisms. In addition, the models of reagent solidification revealed that the stabilization effect of Na2S was better than that of Na2CO3. This model will be useful in the evaluation of the leaching concentrations of heavy metals in fly ash.
Źródło:
Archives of Environmental Protection; 2018, 44, 2; 55-61
2083-4772
2083-4810
Pojawia się w:
Archives of Environmental Protection
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Integrated design of observer based fault detection for a class of uncertain nonlinear systems
Autorzy:
Chen, W.
Khan, A, Q.
Abid, M.
Ding, S. X.
Powiązania:
https://bibliotekanauki.pl/articles/907595.pdf
Data publikacji:
2011
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
detekcja uszkodzeń
obserwator
system nieliniowy
optymalizacja
odporność
fault detection
observer
nonlinear system
optimization
robustness
Opis:
Integrated design of observer based Fault Detection (FD) for a class of uncertain nonlinear systems with Lipschitz nonlinearities is studied. In the context of norm based residual evaluation, the residual generator and evaluator are designed together in an integrated form, and, based on it, a trade-off FD system is finally achieved in the sense that, for a given Fault Detection Rate (FDR), the False Alarm Rate (FAR) is minimized. A numerical example is given to illustrate the effectiveness of the proposed design method.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2011, 21, 3; 423-430
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Raman Spectroscopy of $LiFePO_4$ and $Li_3V_2(PO_4)_3$ Prepared as Cathode Materials
Autorzy:
Ziółkowska, D.
Korona, K.
Kamińska, M.
Grzanka, E.
Andrzejczuk, M.
Wu, S.
Chen, M.
Powiązania:
https://bibliotekanauki.pl/articles/1493017.pdf
Data publikacji:
2011-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.30.Hv
82.80.Gk
82.47.Aa
Opis:
Structure of samples of lithium iron vanadium phosphates of different compositions were investigated by X-rays, electron microscopy and Raman spectroscopy. The investigated salts were mainly of olivine-like and NASICON-like structures. The X-ray diffraction and the Raman scattering show different crystalline structures, which is probably caused by difference between cores of the crystallites (probed by X-rays) and their shells (probed by the Raman scattering). Most of the Raman spectra were identified with previously published data, however in the samples with high vanadium concentration we have observed new, not reported earlier modes at 835 $cm^{-1}$ and 877 $cm^{-1}$, that we identified as oscillations related to $V_2O_7^{4-}$ or $VO_4^{3-}$ anions.
Źródło:
Acta Physica Polonica A; 2011, 120, 5; 973-975
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
XANES Study of La$\text{}_{0.75-x}$Gd$\text{}_{x}$Ca$\text{}_{0.25}$MnO$\text{}_{3-δ}$ Solid Solutions
Autorzy:
Drozd, V. A.
Pęka̶a, M.
Liu, R. S.
Lee, J.-F.
Chen, J. M.
Powiązania:
https://bibliotekanauki.pl/articles/2046755.pdf
Data publikacji:
2006-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.47.Lx
61.10.Ht
Opis:
A series of solid solutions La$\text{}_{0. 75-x}$Gd$\text{}_{x}$Ca$\text{}_{0.25}$MnO$\text{}_{3-δ}$ with 0.0≤x≤0.75 was prepared via carbonate precursor precipitation method. Final sintering was performed at 1250ºC in oxygen flow atmosphere. The samples obtained were characterized by scanning electron microscope, X-ray diffraction measurements. Oxygen stoichiometry was analyzed by iodometric titration method. X-ray absorption spectroscopic methods of Mn L-edge and Mn K-edge X-ray absorption near edge structure were used to study oxidation state of manganese in the solid solutions and elucidate features of their local crystal structure. Orthorhombic crystal structure characteristics of the solid solutions were refined by Rietveld method. An increase in oxygen deficiency and average manganese oxidation state were found to accompany Gd concentration increase in La$\text{}_{0.75-x}$Gd$\text{}_{x}$Ca$\text{}_{0.25}$MnO$\text{}_{3-δ}$. These results are consistent with Mn L-edge X-ray absorption near edge structure spectra, where a gradual change of Mn oxidation state with Gd concentration increase was detected. Origins of oxygen deficiency La$\text{}_{0.75- x}$Gd$\text{}_{x}$Ca$\text{}_{0.25}$MnO$\text{}_{3-δ}$ are discussed in terms of structural disorder caused by Gd substitution for La.
Źródło:
Acta Physica Polonica A; 2006, 109, 4-5; 583-589
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Aboveground biomass and vertical distribution of crown for Taiwan red cypress 20 years after thinning
Autorzy:
Yen, T.-M.
Lee, J.-S.
Li, Ch.-L.
Chen, Y.-T.
Powiązania:
https://bibliotekanauki.pl/articles/41445.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Instytut Dendrologii PAN
Opis:
The aim of this study was to analyze the influence of thinning on the different growth stages of the Taiwan red cypress (Chamaecyparis formosensis Matsum) on the aboveground biomass allocation patterns and vertical distribution of foliage and branch biomass at the tree level. Although numerous studies in various fields have focused on the influence of thinning effects for Taiwan red cypress, few have assessed the aboveground biomass allocation of different growth stages, or conducted a long-term thinning observation. In this study, we examined 3 even-aged plantations in central Taiwan. In 1982, 3 stands, at ages 7, 15, 21 years, simultaneously began thinning trials. A thinning study was conducted once 20 years ago, and we assessed the long-term effects. The effects of thinning in each of the stands were analyzed and compared at the tree level 20 years later. Each component of the aboveground biomass (foliage, branches, and boles) increased with the thinning intensity, regardless of the age category of the trees; however, the crown mass/ aboveground tree mass appeared the same for each tree age category, regardless of the thinning intensity. We inferred that this phenomenon might result from the same proportional increase of crown mass and aboveground tree mass as the thinning intensity was increased. An allometric function was used to quantify the vertical distribution of the foliage and branch biomass; the results showed an increase in the accumulation of the branch biomass at lower heights following thinning, and the same trend was apparent in all 3 plantations.
Źródło:
Dendrobiology; 2013, 70
1641-1307
Pojawia się w:
Dendrobiology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Genetic analysis of 38 double-flowered amaryllis (Hippeastrum hybridum) cultivars based on SRAP markers
Autorzy:
Xiong, M.
Yang, S.
Wang, Y.
Chen, D.
Wang, X.
Zhou, D.
Wei, Z.
Powiązania:
https://bibliotekanauki.pl/articles/12994499.pdf
Data publikacji:
2021
Wydawca:
Uniwersytet Przyrodniczy w Lublinie. Wydawnictwo Uniwersytetu Przyrodniczego w Lublinie
Źródło:
Acta Scientiarum Polonorum. Hortorum Cultus; 2021, 20, 3; 15-25
1644-0692
Pojawia się w:
Acta Scientiarum Polonorum. Hortorum Cultus
Dostawca treści:
Biblioteka Nauki
Artykuł
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