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Tytuł:
Experimental Evidence for Jahn-Teller Transition in a Fe(II)Fe(III) Bimetallic Oxalate
Autorzy:
Tang, G.
He, Y.
Xu, F.
Zhang, Q.
Powiązania:
https://bibliotekanauki.pl/articles/1400401.pdf
Data publikacji:
2013-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Xx
76.80.+y
Opis:
Bimetallic oxalate ${[N-(n-C_4H_9)_4][FeFe(C_2O_4)_3]}_{n}$ has been investigated by the Mössbauer spectroscopy. The Mössbauer studies confirm that high-spin Fe(III) (S=5/2) and Fe(II) (S=2) ions are present in the compound. These spectra above 60 K consist of three quadrupole doublets, indicating that there are three different Fe sites in the material. The Mössbauer results reveal that spontaneous magnetization of Fe(II) sublattices increases more steeply than that of Fe(III) sublattices as the temperature decreases from $T_{C}$. Great increase of quadrupole splitting at 50 K provides compelling evidence for the predicted Jahn-Teller transition.
Źródło:
Acta Physica Polonica A; 2013, 123, 1; 118-120
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Modelling and Calculation of the Initial Ignition Gas Pressure Flow through a Rigid Porous Medium in a 100 mm Ignition Simulator
Autorzy:
Xiao, Z.
Ying, S.
He, W.
Xu, F.
Powiązania:
https://bibliotekanauki.pl/articles/358563.pdf
Data publikacji:
2014
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego
Tematy:
ignition
ignition simulator
porous media
propellant
modelling
simulation
Opis:
To acquire a better understanding of the early ignition phenomena in a 100 mm ignition simulator loaded with a packed propellant bed, a theoretical model of the ignition gas flow through the rigid porous medium was developed. Three pressure gauges were installed in the lateral side of the ignition simulator for post ignition measurement of the chamber pressure. The pseudo-propellant loaded into the chamber was similar in size to the standard 13/19 single-base cylindrical propellant. It was composed of a rigid ceramic composite with low thermal conductivity. It was assumed that the pseudo-propellant bed was rigid in contrast to the assumption of an elastic porous medium. The calculated pressure values were well verified by the experimental data at a low loading density of the pseudo-propellant bed of 0.18 g•cm-3. However, there was still error between the experimental and the calculated results in the early pressure peak position closest to the ignition primer when the loading density of the pseudo-propellant bed was increased to 0.73 and 1.06 g•cm-3. This error is attributed to the change in local permeability of the pseudo-propellant bed at high loading densities, which is assumed, for ease of modelling, to be constant in the model. These calculations may enable a better understanding of the physical processes of ignition gas flow in an ignition simulator loaded with a pseudo-propellant bed.
Źródło:
Central European Journal of Energetic Materials; 2014, 11, 4; 475-489
1733-7178
Pojawia się w:
Central European Journal of Energetic Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Robust MPC for actuator-fault tolerance using set-based passive fault detection and active fault isolation
Autorzy:
Xu, F.
Puig, V.
Ocampo-Martinez, C.
Olaru, S.
Niculescu, S. I.
Powiązania:
https://bibliotekanauki.pl/articles/330788.pdf
Data publikacji:
2017
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
fault detection
fault isolation
set theoretic method
fault tolerant control
model predictive control
detekcja uszkodzeń
lokalizacja uszkodzeń
sterowanie tolerujące uszkodzenia
sterowanie predykcyjne
Opis:
In this paper, a fault-tolerant control (FTC) scheme is proposed for actuator faults, which is built upon tube-based model predictive control (MPC) as well as set-based fault detection and isolation (FDI). In the class of MPC techniques, tube-based MPC can effectively deal with system constraints and uncertainties with relatively low computational complexity compared with other robust MPC techniques such as min-max MPC. Set-based FDI, generally considering the worst case of uncertainties, can robustly detect and isolate actuator faults. In the proposed FTC scheme, fault detection (FD) is passive by using invariant sets, while fault isolation (FI) is active by means of MPC and tubes. The active FI method proposed in this paper is implemented by making use of the constraint-handling ability of MPC to manipulate the bounds of inputs. After the system has been detected to become faulty, the input-constraint set of the MPC controller is adjusted to actively excite the system for achieving FI guarantees on-line, where an active FI-oriented input set is designed off-line. In this way, the system can be excited in order to obtain more extra system-operating information for FI than passive FI approaches. Overall, the objective of this paper is to propose an actuator MPC scheme with as little as possible of FI conservatism and computational complexity by combining tube-based MPC and set theory within the framework of MPC, respectively. Finally, a case study is used to show the effectiveness of the proposed FTC scheme.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2017, 27, 1; 43-61
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Nondestructive Evaluation of Rubber Composites Using Terahertz Time Domain Spectroscopy
Niedestrukcyjna metoda oceny kompozytów kauczukowych przy użyciu spektroskopii z wykorzystaniem technologii wykrywania terahercowego
Autorzy:
Xu, F.
Duan Mu, Q. D.
Li, L. J.
Yang, D.
Xia, B.
Powiązania:
https://bibliotekanauki.pl/articles/232361.pdf
Data publikacji:
2018
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Biopolimerów i Włókien Chemicznych
Tematy:
terahertz imaging
rubber composites
nondestructive testing
defects
wykrywanie terahercowe
materiały gumowe
badania nieniszczące
defect gumy
Opis:
In recent years, with the progress of science, more and more detection methods are being used in various fields. However, the nondestructive testing of nonmetallic materials still needs further study. In this paper, an analysis of the time domain characteristics of rubber materials using terahertz detection technology was carried out, obtaining different defect rubber material spectral characteristics as well as imaging results and data. The results show that the THz spectrum imaging technique can detect the thickness of rubber material in the 0.1 ~ 4.0 terahertz band, and the image is clear and the resolution high. Meanwhile the time domain waveform obtained is sensitive to the debonding defects of the sample rubber, is suitable for judging the overall performance of the rubber inner defect detection, and can provide the scientific basis for rubber material performance.
W artykule przedstawiono analizę charakterystyk materiałów gumowych z wykorzystaniem technologii wykrywania terahercowego, uzyskując różne charakterystyki spektralne defektów gumy, a także wyniki i dane obrazowe. Wyniki pokazały, że technika obrazowania widma THz może wykrywać grubość materiału gumowego w paśmie 0,1 ~ 4,0 terahercowym, a obraz jest wyraźny i ma wysoka rozdzielczość. W międzyczasie otrzymany przebieg domeny czasu jest wrażliwy na defekty badanej gumy, jest odpowiedni do oceny ogólnej wydajności wykrywania wewnętrznego defektu gumy i może zapewnić podstawy dla oceny właściwości materiału gumowego.
Źródło:
Fibres & Textiles in Eastern Europe; 2018, 1 (127); 67-72
1230-3666
2300-7354
Pojawia się w:
Fibres & Textiles in Eastern Europe
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Acer truncatum seedlings are more plastic than Quercus variabilis seedlings in response to different light regimes
Autorzy:
Guo, X.
Wang, R.-Q.
Wang, C.D.
Xu, F.
Zhao, S.
Guo, W.-H.
Powiązania:
https://bibliotekanauki.pl/articles/41339.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Instytut Dendrologii PAN
Tematy:
Acer truncatum
seedling
Quercus variabilis
Chinese cork oak
plant response
light regime
irradiance acclimation
chlorophyll fluorescence
morphology
photoinhibition
Opis:
In this study, we investigated responses of the mid-successional species Acer truncatum Bunge and the late-successional species Quercus variabilis Blume to three solar illumination conditions: (1) constant low light (CL), (2) constant high light (CH) and (3) low light first and high light afterwards (LH). The last treatment was to simulate a canopy opening. Both species exhibited increases in biomass, totally and in part, and decreases in leaf water content, specific leaf area and chlorophyll concentrations in LH treatment compared to CL treatment. For A. truncatum, exposure to high light condition (LH) increased crown area, and decreased root to shoot ratio, stem mass ratio and leaf perimeter. However, for Q. variabilis, LH treatment increased stem diameter at ground height, effective quantum yield, photochemical quenching and decreased maximum photosystem II quantum yield. The biomass allocation pattern did not change in Q. variabilis among three light conditions. With respect to newly developed leaves, no significant differences were found in leaf size of Q. variabilis between LH treatment and CH treatment while that of A. truncatum decreased in LH treatment. All chlorophyll fluorescence parameters in newly developed oak leaves in LH treatment increased compared to those of CH treatment while no difference was found for A. truncatum between LH and CH treatment. A. truncatum displayed a greater overall plasticity than Q. variabilis although the oak seedlings have a greater plasticity with respect to chlorophyll concentration and chlorophyll fluorescence parameters. A. truncatum should be a better candidate for vegetation recovery, especially in places with heterogeneous light conditions.
Źródło:
Dendrobiology; 2016, 76
1641-1307
Pojawia się w:
Dendrobiology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Protective effect of lithium chloride on pulmonary injury caused by Actinobacillus pleuropneumoniae via inhibition of GSK-3β-NF-κB-dependent pathway
Autorzy:
Zhang, Y.
Xu, W.
Tang, Y.
Huang, F.
Powiązania:
https://bibliotekanauki.pl/articles/16539075.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czasopisma i Monografie PAN
Tematy:
porcine contagious pleuropneumonia
mouse model
lithium chloride
toll-likereceptor 4
GSK-3β-NF-κB-dependent pathways
Opis:
Porcine contagious pleuropneumonia (PCP) is a very serious respiratory disease which is difficult to prevent and treat. In this study, the therapeutic effects of lithium chloride (LiCl) on PCP were examined using a mouse model. A mouse model of PCP was established by intranasal infections with Actinobacillus pleuropneumoniae (App). Histopathological analysis was performed by routine paraffin sections and an H-E staining method. The inflammatory factors, TLR4 and CCL2 were analyzed by qPCR. The expression levels of p-p65 and pGSK-3ß were detected using the Western Blot Method. The death rates, clinical symptoms, lung injuries, and levels of TLR-4, IL-1ß, IL-6, TNF-α, and CCL2 were observed to decrease in the App-infected mice treated with LiCl. It was determined that the LiCl treatments had significantly reduced the mortality of the App-infected cells, as well as the expressions of p-p65 and pGSK-3ß. The results of this study indicated that LiCl could improve the pulmonary injuries of mice caused by App via the inhibition of the GSK-3β-NF-κB-dependent pathways, and may potentially become an effective drug for improving pulmonary injuries caused by PCP.
Źródło:
Polish Journal of Veterinary Sciences; 2022, 25, 1; 35-44
1505-1773
Pojawia się w:
Polish Journal of Veterinary Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The effect of surface functional groups of nanosilica on the properties of polyamide 6/SiO2 nanocomposite
Autorzy:
Xu, Q.
Chen, F.
Li, X.
Zhang, Z.
Powiązania:
https://bibliotekanauki.pl/articles/779538.pdf
Data publikacji:
2013
Wydawca:
Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie
Tematy:
nanosilica
polyamide 6
nanocomposite
in situ polymerization
Opis:
The present study investigated the effect of the surface functional groups of nanosilica on the interfacial, crystallization, and thermal stability of polyamide 6/SiO2 (PA6/SiO2) nanocomposite, in which nanosilica was modified in situ with both 3-triethoxysilylpropylamine and 3-methacryloxypropyltrimethoxy silane¬ (KH-550 and KH-570). The FTIR analysis results showed the chemical bonding action between the reacting amino groups of nanosilica and end carboxyl groups of polyamide 6 enhanced with increasing the ratio of KH-550 and KH-570. The XRD spectrum indicated that the crystal structure of PA6/SiO2 nanocomposites tended to form α crystal type that was beneficial to an improvement of mechanical properties, and which was in agreement with the results of mechanical strength measurements. It was also found that crystallization temperature and crystallization rate of PA6/SiO2 nanocomposites were lower than that of neat polyamide 6.
Źródło:
Polish Journal of Chemical Technology; 2013, 15, 3; 20-24
1509-8117
1899-4741
Pojawia się w:
Polish Journal of Chemical Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
System for Calibrating Analogue Merging Units in Absence of Synchronization Signals
Autorzy:
Cheng, H.-M.
Huang, Q.-F.
Ji, F.
Xu, Q.
Liu, J.
Tian, Z.
Powiązania:
https://bibliotekanauki.pl/articles/221084.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
intelligent substation
analogue merging unit
peer-to-peer communication
calibration system
synchronization signal
Opis:
Synchronization signals are requisite for calibrating electrical measurement devices with digital output when using conventional calibration methods. However, since the signal sampling process of the analogue merging units (MUs) operating in an intelligent substation does not rely on external synchronization signals, accuracy calibration without the use of synchronization signals is of particular importance in order to guarantee the measurement accuracy in practical situations. So far, very little research on calibration systems independent of synchronization signals has been performed. This paper presents a design of the calibration system without dependence on synchronization signals. To verify the feasibility of the proposed design, the designed system and a conventional calibration system have been employed in testing the accuracy of the same analogue MU of a 0.2 accuracy class. The comparison of the test results shows that the differences of ratio errors are below 0.02%, and the maximum difference of phase errors is about 4′. This paper also provides a new efficient and significant calibration method which does not require any external synchronization signals.
Źródło:
Metrology and Measurement Systems; 2018, 25, 1; 129-138
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
One step purification of impurities in the leachate of weathered crust elution-deposited rare earth ores
Autorzy:
Zhou, F.
Feng, J.
Wang, Z.
Xu, Y.
Zhang, Z.
Chi, R.
Powiązania:
https://bibliotekanauki.pl/articles/110333.pdf
Data publikacji:
2017
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
leachate
weathered crust
rare earth ore
leachate purification
precipitation
Opis:
It is necessary to control and reduce the high content of Al3+, Cu2+ and Pb2+ ions in the leachate of weathered crust elution-deposited rare earth ore to facilitate the rare earth recovery and the quality of rare earth products. Neither NH4HCO3 nor Na2S are suitable for removal of all impurity ions and meanwhile maintain high rare earth recovery. Conventionally, NH4HCO3 is firstly adopted to remove Al3+, and then Cu2+ and Pb2+ are removed by using Na2S. This two steps purification process is quite long and results in lots of complication in operation. In this paper, a one-step purification by using the compound of NH4HCO3 and Na2S was proposed to remove Al3+, Cu2+ and Pb2+. The results showed that after purification 89% Cu, 92% Pb and 74% Al were removed from the leachate solution by using 0.1 M compound of NH4HCO3/Na2S, while maintaining 89% rare earth. The optimal purification parameters were: volume ratio of NH4HCO3 to Na2S of 9:1, volume ratio of compound to leachate of 0.05:1, precipitation time of 30 min.
Źródło:
Physicochemical Problems of Mineral Processing; 2017, 53, 2; 1188-1199
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optical properties of Nd:YbVO4 crystal
Autorzy:
Liu, F Q
Sun, S Q
Gao, C Y
Xu, J Q
Powiązania:
https://bibliotekanauki.pl/articles/174689.pdf
Data publikacji:
2015
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
Nd
YbVO4 crystal
Judd-Ofelt theory
energy transfer
Opis:
Optical characteristics of a new laser crystal Nd:YbVO4 were studied. The optical parameters of a-cut and c-cut Nd:YbVO4 crystals were calculated by the Judd–Ofelt theory. The absorption crosssection of a-cut Nd:YbVO4 crystal was 5.34×10–20 cm2 at 808 nm, while it was 4.20×10–18 cm2 of c-cut Nd:YbVO4 crystal. The properties of energy transfer between Nd and Yb ions in Nd:YbVO4 crystal were discussed. In the fluorescence spectra, a peak at 472 nm appeared, which resulted from the coupling interaction between two Yb ions.
Źródło:
Optica Applicata; 2015, 45, 1; 63-70
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Morphological analysis of organo-montmorillonites via MD simulations
Autorzy:
Karataş, Deniz
Tekin, Adem
Can, Muhammed F.
Xu, Zhenghe
Çelik, Mehmet S.
Powiązania:
https://bibliotekanauki.pl/articles/2146936.pdf
Data publikacji:
2022
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
organo-montmorillonite
tetradecyl dimethyl ethyl benzyl ammonium chloride
molecular dynamics simulation
cation exchange capacity
binding energy
Opis:
Adsorption on clay surfaces has been studied intensively in recent years. The most curious subject of these studies, which are generally experimental, is how the surfactants are adsorbed at the atomic level to the surface. In this study, the adsorption of quaternary amine salt (tetradecyl dimethyl ethyl benzyl ammonium chloride–TDEBAC) to sodium montmorillonite (Na-MMT) with various cation exchange capacities (CEC) was investigated by using Molecular Dynamics (MD) simulation. In the simulations, as in the experimental studies, it was revealed that the surfactants were both adsorbed on to basal surfaces and settled between the layers. From the morphological analysis obtained from MD simulations, it was calculated that the inter-molecular interaction between the layers was higher than on the basal surface. For example, for the model with 118 CEC motif, the binding energy of all three surfactants in the models with the hydrophilic heads facing the same direction was calculated as -678.18 kcal/mol at the basal surface, while this value was found to be -688.90 kcal/mol in the interlayer. The more striking result is that in the simulations made by turning the head of the middle one of the three surfactants towards the tails of the right and left ones, only -34.86 kcal/mol binding energy was calculated on the basal surface, while this value was -525.63 kcal/mol in the interlayer. As compared middle reversed surfactant models with the same direction ones, despite increased CEC the intermolecular interaction decreased for the basal surface, but the interaction increased between the layers.
Źródło:
Physicochemical Problems of Mineral Processing; 2022, 58, 5; art. no. 152499
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Isolation and genetic analysis of a variant porcine epidemic diarrhea virus in China
Autorzy:
Li, R.-f.
Tian, X.-g.
Liu, Y.
Xu, J.
Liu, D.-y.
Powiązania:
https://bibliotekanauki.pl/articles/30492.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Opis:
Porcine epidemic diarrhea virus (PEDV) is having a severe effect on the pig breeding industry in central China. The mucosa and the content of the small intestine from newborn pre-weaned piglets with diarrhea were tested for the presence of PEDV by molecular and morphologic methods, and found to be positive. Negative-staining electron microscopy (EM) revealed the presence of coronavirus- like particles in the samples. The result of molecular detection by nested RT-PCR based on the amplification of the M gene was positive. Using a novel alternative method we successfully propagated the PEDV strain (CH/QX-2) in Vero cells, confirmed by ultrathin sections of the cells and Immunofluorescence assay (IFA). Phylogenetic analysis based on the partial S gene showed that the CH/QX-2 isolate was genetically closer to strains more commonly found in China, but differed genetically from two domestic strains (CH/S, 1986 and LZC, 2007), Korean strains (DR13, 2007), and the vaccine strain (CV777 vs) currently being used in China. CH/QX-2 formed a unique clade in the derived phylogenetic tree indicating that the CH/QX-2 strain currently circulating in central China is a new variant of PEDV. This study extends current knowledge on the diversity and epidemiology of PEDV.
Źródło:
Polish Journal of Veterinary Sciences; 2016, 19, 1
1505-1773
Pojawia się w:
Polish Journal of Veterinary Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Reliability analysis of machining center based on the field data
Analiza niezawodnościowa centrum obróbkowego w oparciu o dane terenowe
Autorzy:
Yang, Z. J.
Chen, Ch. H.
Chen, F.
Hao, Q. B.
Xu, B. B.
Powiązania:
https://bibliotekanauki.pl/articles/302160.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Polskie Naukowo-Techniczne Towarzystwo Eksploatacyjne PAN
Tematy:
analiza uszkodzeń
centrum obróbkowe
polityka utrzymania ruchu
proces spełniający prawo potęgowe
system naprawialny
failure analysis
machining center
maintenance policy
power-law process
repairable system
Opis:
Machining center is the complex machinery, with high level automation and complicated structures, so there are lots of failures. When a random failure occurs, the failed machining center stops and causes a production line or even the whole workshop to stop functioning. The frequent failure leads to the low levels of reliability and production rate. In order to help users and manufacturers optimize maintenance policy to improve the reliability for machining center, this paper presents descriptive statistics of the failure data and develops the failure trend using power-law process, simultaneously establishes the routine inspection and regular inspection as well as the sequential preventive maintenance under maintenance cost constraints. The proposed model could be a useful tool to assess the current conditions, predict reliability and optimize the machining center maintenance policy.
Centrum obróbkowe to skomplikowany mechanizm o wysokim poziomie automatyzacji oraz złożonej konstrukcji, w związku z czym ulega licznym uszkodzeniom. Przy wystąpieniu przypadkowej awarii, uszkodzone centrum obróbkowe przestaje działać i powoduje zatrzymanie linii produkcyjnej a nawet całego oddziału produkcyjnego. Częste awarie obniżają poziom niezawodności oraz tempo produkcji. Aby pomóc użytkownikom i producentom zoptymalizować politykę utrzymania ruchu w celu poprawy niezawodności centrów obróbkowych, w niniejszym artykule przedstawiono statystyki opisowe dotyczące danych o uszkodzeniach i opracowano trend uszkodzeń w oparciu o proces spełniający prawo potęgowe. Jednocześnie ustalono zasady rutynowej inspekcji i okresowych przeglądów, jak również sekwencyjnej obsługi zapobiegawczej przy ograniczonych wydatkach na utrzymanie ruchu. Proponowany model może być użytecznym narzędziem dla potrzeb oceny aktualnych warunków oraz przewidywania niezawodności w celu optymalizacji polityki utrzymania ruchu centrum obróbkowego.
Źródło:
Eksploatacja i Niezawodność; 2013, 15, 2; 147-155
1507-2711
Pojawia się w:
Eksploatacja i Niezawodność
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Finite Element Modeling for the Uni-Axial Tensile Behaviour of Metallic Warp-Knitted Fabric
Zastosowanie metody elementów skończonych (FEM) do przewidywania jednoosiowego rozciągania dzianin metalicznych
Autorzy:
Xu, H.-Y.
Jiang, J.-H.
Chen, N.-L.
Lin, F.-B.
Shao, H.-Q.
Powiązania:
https://bibliotekanauki.pl/articles/231781.pdf
Data publikacji:
2018
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Biopolimerów i Włókien Chemicznych
Tematy:
warp-knitted fabric
finite element analysis
tensile behavior
metallic
TexGen
dzianina osnowowa
analiza elementów skończonych
proces rozciągania
dzianina metaliczna
Opis:
The finite element analysis method (FEM), for its advantages of lower time and economic costing in predicting the mechanical properties of fabrics, was applied to warp-knitted fabrics. In this paper, two bar warp-knitted fabric knitted with wires was used as reflecting mesh antennas. Firstly the loop unit of the metallic warp-knitted fabric was simulated in 3-D by TexGen software. Secondly the 3-D loop unit model was inputted into ABAQUS software to form a model of the metallic warp-knitted fabric sheet for uni-axial tension analysis. Thirdly numerical results were obtained after setting the parameters in ABAQUS. Finally numerical results were verified by uni-axial tensile experiments on the metallic warp-knitted fabric. The results showed that the simulation was in good agreement with the experimental tensile process, where the transfer of yarns between loops when in low fabric elongation and in yarn elongation when in high fabric elongation were simulated by FEM of warp-knitted fabric in the tensile process. Also the same trend of tensile force was found in experiment and FEM results. Therefore it can be concluded that FEM can be used to predict the mechanical properties of warp-knitted fabric with a complex structure.
Do przewidywaniu mechanicznych właściwości dzianin metalicznych zastosowano metodę elementów skończonych (FEM). Symulacji 3D dzianin dokonano przy użyciu dwóch rodzajów oprogramowania: TexGen i ABAQU. Wyniki symulacji zweryfikowano eksperymentalnie. Stwierdzono, że symulacja charakteryzowała się zgodnością z eksperymentalnie przeprowadzonym procesem rozciągania. Na podstawie wyników stwierdzono, że metoda elementów skończonych (FEM) może być z powodzeniem wykorzystywana do przewidywania mechanicznych właściwości dzianin o złożonej strukturze.
Źródło:
Fibres & Textiles in Eastern Europe; 2018, 2 (128); 49-54
1230-3666
2300-7354
Pojawia się w:
Fibres & Textiles in Eastern Europe
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Combustion Characteristics and Mechanism of Boron-based, Fuel-rich Propellants with Agglomerated Boron Powder
Autorzy:
Xu, H. -X.
Pang, W.-Q.
Guo, H.-W.
Zhao, F.-Q.
Wang, Y.
Sun, Z.-H.
Powiązania:
https://bibliotekanauki.pl/articles/358733.pdf
Data publikacji:
2014
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego
Tematy:
analytical chemistry
boron-based fuel-rich solid propellants
agglomerated boron powder
combustion performance
combustion mechanism
Opis:
In order to extend the burning rate of boron-based, fuel-rich solid propellants with agglomerated boron powder, the effects of the boron content, the AP content, and of the magnesium powder content, on the burning rate and pressure exponent have been studied systematically. It has been shown that when the AP content is constant, the burning rate of the propellants increases with an increase in the agglomerated boron content. Furthermore, the burning rate and pressure exponent increase with increasing the contents of AP and magnesium powder. By means of single colour frame amplification photography and combustion wave tests, the combustion mechanism of these propellants has been investigated. It has been shown that the flame of the propellants becomes brighter by increasing the AP content, the dT/dxcp and dT/dxgp of the propellant FR-5 being around 6815 and 5789 °C/mm respectively, higher than those of FR-4, resulting in greater burning rates. The Ts of these propellants is above 683 °C, which is higher than the decomposition peak temperatures of agglomerated boron powder and of propellants (about 649 °C), which indicates that agglomerated boron powder is partially oxidized on the combustion surface, and the heat released from it may be beneficial to the combustion of the propellants.
Źródło:
Central European Journal of Energetic Materials; 2014, 11, 4; 575-587
1733-7178
Pojawia się w:
Central European Journal of Energetic Materials
Dostawca treści:
Biblioteka Nauki
Artykuł

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