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Tytuł:
Photoelectron Emission Microscopy and its Application to the Study of Polymer Surfaces
Autorzy:
Cossy-Favre, A.
Diaz, J.
Anders, S.
Padmore, H.
Liu, Y.
Samant, M.
Stöhr, J.
Brown, H.
Russell, T. P.
Powiązania:
https://bibliotekanauki.pl/articles/1964108.pdf
Data publikacji:
1997-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.16.Ms
73.61.Ph
64.75.+g
Opis:
The X-ray photoelectron emission microscopy at the Advanced Light Source has a spatial resolution of 0.2 microns at an accelerating voltage of 12 kV. The tunability of the photon energy is used to provide chemical state information using near edge X-ray absorption fine structure spectroscopy on the sub-micrometer scale. The homogeneity of thin films of polymer blends was studied for various film thicknesses. The polystyrene/polyvinylmethylether film of 194 Å showed protrusions of 2-3 μm diameter with an enriched polystyrene content while the polystyrene/polystyreneacrylonitrile 504 Å thick films showed 5-6 μm segregated regions without any topological structure.
Źródło:
Acta Physica Polonica A; 1997, 91, 5; 923-927
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Transport and Magnetic Properties of Low Temperature Annealed Ga$\text{}_{1-x}$Mn$\text{}_{x}$As
Autorzy:
Kuryliszyn, I.
Wojtowicz, T.
Liu, X.
Furdyna, J. K.
Dobrowolski, W.
Broto, J.-M.
Goiran, M.
Portugall, O.
Rakoto, H.
Raquet, B.
Powiązania:
https://bibliotekanauki.pl/articles/2035604.pdf
Data publikacji:
2002
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Pp
75.50.Dd
81.40.Rs
Opis:
We present the results of low temperature annealing studies of Ga$\text{}_{1-x}$Mn$\text{}_{x}$As epilayers grown by low temperature molecular beam epitaxy in a wide range of Mn concentrations (0.01
Źródło:
Acta Physica Polonica A; 2002, 102, 4-5; 659-665
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A Compact High Current Vacuum Diode Based on a Ceramic-Metal Welding Interface
Autorzy:
Xun, T.
Zhang, J.
Yang, H.
Wang, Y.
Liu, Z.
Powiązania:
https://bibliotekanauki.pl/articles/1807886.pdf
Data publikacji:
2009-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
52.59.Mv
73.20.-r
84.70.+p
Opis:
For one kind of high current diodes composed of a ceramic-metal welding vacuum interface, the electrical design was presented. For compactness, a radial type insulator and a cone-column anode crust were adopted. The shielding methods around cathode and anode region were applied to mitigate the influence of welding solder to vacuum flashover. Finite Element Analysis (FEA) simulation results indicated that by adjusting the anode outline and shielding shape, the electric fields along the ceramic were well distributed. High voltage test was conducted on a long-pulse accelerator and experimental results confirm the theoretic design: the diode can stably hold on 400 kV and 200 ns voltage pulse.
Źródło:
Acta Physica Polonica A; 2009, 115, 6; 1013-1015
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Catalytic decomposition of toluene over La1-xSr xMnO3/palygorskite synthesized catalysts
Autorzy:
Song, L.
Chen, T.
Chen, D.
Chen, Y.
Xie, J.
Liu, H.
Powiązania:
https://bibliotekanauki.pl/articles/207996.pdf
Data publikacji:
2013
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
catalysts
manganese
manganese oxide
toluene
transmission electron microscopy
X ray diffraction
Palygorskite
katalizatory
mangan
tlenek manganu
toluen
transmisyjna mikroskopia elektronowa
dyfrakcja promieniowania rentgenowskiego
Opis:
Palygorskite (PG) supported La1-xSrxMnO3 catalysts were fabricated by copreripitation. The catalysts were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), specific surface area (SSA) and H2 temperature programmed reduction (H 2-TPR). Catalytic activity for VOCs was examined by using toluene as a model compound. The results show that the surface area as well as mechanical strength of catalysts increase substantially after catalysts loaded in PG. XRD patterns show that after calcination at 700 0C, PG as a support in 9% LaMn03/PG and 9% La0.7Sr0.3MnO3/PG was transformed into amorphous phase and the morphology was not destroyed. It was well established that the main reductive components are factually Mn(III) or Mn(IV) oxides in catalysts based on the results of TPR. It was also found that Mn(IV) increases while Mn(III) reduces responding with the increasing amount of Sr. Toluene conversion rate of as-preparedμ% La1-xSr xMnO3/PG increases with the increasing values of x and μ when x=0-0.3 and μ = 3-9%. Toluene can be converted completely at 285 0C by 9% La0.7Sr0.3MnO3/PG catalyst while no significant change was observed after addition on the doping and loading amount of Sr. During a 100 h stability experiment of 9% La 0.7Sr0.3MnO3/PG catalyst, toluene removal was found to be above 95%.
Źródło:
Environment Protection Engineering; 2013, 39, 3; 31-42
0324-8828
Pojawia się w:
Environment Protection Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Hydrides formed in ZrCo2 - based intermetallic compounds under high hydrogen pressure
Wodorki wytwarzane pod wysokimi ciśnieniami wodoru ze związków międzymetalicznych na osnowie ZrCo2
Autorzy:
Filipek, S. M.
Liu, Ru-Shi
Kuriyama, N.
Takeichi, N.
Tanaka, H.
Bulyk, I. I.
Kuo, H.-T.
Tu, M.-H.
Kochman, M.
Powiązania:
https://bibliotekanauki.pl/articles/350834.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
wodorki
wysokie ciśnienie wodoru
hybrides
high hydrogen pressure
Laves phases
Opis:
The hydrides of zirconium based pseudobinary alloys Zr(Co1-xTx)2, (T = Fe, V or Cr) and Zr1-xRxCo2 (R = Y, La, Pr) were synthesized under 1.2 GPa of hydrogen pressure. It was revealed that partial substitution of cobalt by V, Cr or Fe increases hydrogen absorption capacity and stability of derived hydrides. Especially, it was found that ZrCo1:8V0:2 alloy exposed to high hydrogen pressure can absorb 50% more hydrogen than pure ZrCo2 and the hydride ZrCo1:8V0:2Hy has surprisingly high stability. Substitution of zirconium by Y, La or Pr in ZrCo2 alloys improved hydrogen absorption but hydrides derived from La and Pr substituted alloys were less stable than ZrCo2H2. Only for Zr0:7Y0:3Co0:2Hy the hydrogen absorption was higher and desorption rate markedly smaller comparing ZrCo2H2.
Pod wysokim ciśnieniem wodoru rzędu 1.2 GPa otrzymano szereg wodorków na osnowie pseudobinarnych stopów cyrkonu o następujących składach: Zr(Co1-xTx)2, (T = Fe, V or Cr) oraz Zr1-xRxCo2 (R = Y, La, Pr). Wykazano, że częściowe podstawienie kobaltu wanadem, chromem lub żelazem zwiększa zdolność absorpcyjną stopów i stabilność tworzących się wodorków. W szczególności okazało się, że pod wysokim ciśnieniem wodoru ZrCo1:8V0:2 absorbuje o 50% więcej wodoru aniżeli ZrCo2, a co więcej otrzymany z tego stopu wodorek ma nieoczekiwanie wysoką stabilność. Częściowe zastąpienie cyrkonu itrem, lantanem lub prazeodymem podwyższało wprawdzie zdolność absorpcyjną wodoru ale jednocześnie otrzymane wodorki zawierające lantan lub prazeodym były mniej stabilne aniżeli ZrCo2H2. Jedynie dla Zr0:7Y0:3Co0:2Hy odnotowano wyższą absorpcje wodoru i niższą szybkość jego desorpcji aniżeli w przypadku ZrCo2H2.
Źródło:
Archives of Metallurgy and Materials; 2013, 58, 1; 223-226
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Postural and Muscular Responses While Viewing Different Heights of Screen
Autorzy:
Lee, T. H.
Liu, T. Y.
Powiązania:
https://bibliotekanauki.pl/articles/90519.pdf
Data publikacji:
2013
Wydawca:
Centralny Instytut Ochrony Pracy
Tematy:
visual display terminal
posture
viewing angle
pozycja przy pracy
kąt widzenia
ekran
praca przy komputerze
Opis:
This study aimed to examine the effects of visual display terminal (VDT) viewing angle on human postural angle and muscular activity. The participants’ neck, thoracic bending, and trunk inclination angles; and the activity of sternocleidomastoid, trapezius, splenius capitis, and erector spinae at 5 viewing angles (+400, +200, 00, –200, and –400) of a VDT screen were collected for 1 min. This study showed that neck and thoracic bending angles increased with viewing angle, while viewing angle did not significantly affect trunk inclination angle. In addition, the activity of trapezius and erector spinae increased when viewing a higher or lower VDT screen height compared with viewing a horizontal VDT screen height; however, the activity of splenius capitis decreased with viewing angle.
Źródło:
International Journal of Occupational Safety and Ergonomics; 2013, 19, 2; 251-258
1080-3548
Pojawia się w:
International Journal of Occupational Safety and Ergonomics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Synthesis, Crystal Structure, and Properties of a Novel, Highly Sensitive Energetic, Coordination Compound: Iron (II) Carbohydrazide Perchlorate
Autorzy:
Liu, R.
Zhou, Z.
Qi, S.
Yang, L.
Wu, B.
Huang, H.
Zhang, T.
Powiązania:
https://bibliotekanauki.pl/articles/358343.pdf
Data publikacji:
2013
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego
Tematy:
iron (II) carbohydrazide perchlorate
energetic material
high
sensitivity
DFT
energy gap
Opis:
A single crystal of iron (II) carbohydrazide perchlorate [FeII (CHZ)3](ClO4)2 (FeCP), a novel, lead-free, energetic coordination compound, was synthesized and its structure determined by X-ray single crystal diffraction for the frst time. The crystal belongs to the monoclinic system P2(1)/n space group, with a = 1.0066(2) nm, b = 0.8458(2) nm, c = 2.1194(4) nm, β = 100.693(3)° and Z = 4. The central Fe(II) ion is coordinated to three bidentate carbohydrazide units through the carbonyl oxygen atom and an amino nitrogen atom, forming a six-coordinated, non-centrosymmetric complex cation. The thermal analyses by differential scanning calorimetry and thermogravimetry show that the onset temperature of thermal decomposition (152.7 °C) and the critical temperature of thermal explosion of FeCP (161.2 °C) are both much lower than those of other transition metal carbohydrazide perchlorate compounds, and also those of some other primary explosives in service. FeCP has a high enthalpy of combustion, as measured by oxygen bomb calorimetry. The impact, friction and fame sensitivity tests indicate that FeCP is extremely sensitive and hazardous. Unexpected explosions occurred even during the operational processes. In order to explore the intrinsic cause of these explosions, theoretical calculations of the orbital energies were performed based on DTF. These results reveal that the impact sensitivity is positively correlated with the energy gap between HOMO and LUMO: the smaller energy gap results in the higher impact sensitivity.
Źródło:
Central European Journal of Energetic Materials; 2013, 10, 1; 17-36
1733-7178
Pojawia się w:
Central European Journal of Energetic Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Free chlorine loss during spraying of membraneless acidic electrolyzed water and its antimicrobial effect on airborne bacteria from poultry house
Autorzy:
Zhao, Y.
Xin, H.
Zhao, D.
Zheng, W.
Tian, W.
Ma, H.
Liu, K.
Hu, H.
Wang, T.
Soupir, M.
Powiązania:
https://bibliotekanauki.pl/articles/49243.pdf
Data publikacji:
2014
Wydawca:
Instytut Medycyny Wsi
Źródło:
Annals of Agricultural and Environmental Medicine; 2014, 21, 2
1232-1966
Pojawia się w:
Annals of Agricultural and Environmental Medicine
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Amorphous Dielectric Thin Films with Extremely Low Mechanical Loss
Amorficzne cienkie warstwy dielektryczne z bardzo małą wielkością strat mechanicznych
Autorzy:
Liu, X.
Queen, D. R.
Metcalf, T. H.
Karel, J. E.
Hallman, F.
Powiązania:
https://bibliotekanauki.pl/articles/353256.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
internal friction
amorphous silicon
elastic modulus
speed of sound
tunneling systems
tarcie wewnętrzne
krzem amorficzny
moduł sprężystości
prędkość dźwięku
Opis:
The ubiquitous low-energy excitations are one of the universal phenomena of amorphous solids. These excitations dominate the acoustic, dielectric, and thermal properties of structurally disordered solids. One exception has been a type of hydrogenated amorphous silicon (α-Si:H) with 1 at.% H. Using low temperature elastic and thermal measurements of electron-beam evap-orated amorphous silicon (α-Si), we show that TLS can be eliminated in this system as the films become denser and more structurally ordered under certain deposition conditions. Our results demonstrate that TLS are not intrinsic to the glassy state but instead reside in low density regions of the amorphous network. This work obviates the role hydrogen was previously thought to play in removing TLS in α-Si:H and favors an ideal four-fold covalently bonded amorphous structure as the cause for the disappearance of TLS. Our result supports the notion that α-Si can be made a “perfect glass” with “crystal-like” properties, thus offering an encouraging opportunity to use it as a simple crystal dielectric alternative in applications, such as in modern quantum devices where TLS are the source of dissipation, decoherence and 1/f noise.
Wszechobecne niskoenergetyczne wzbudzenia są jednym z powszechnych zjawisk w amorficznych ciałach stałych. Wzbudzenia te dominują akustyczne, dielektryczne i termiczne właściwości strukturalnie nieuporządkowanych ciał stałych. Wyjątkiem jest rodzaj uwodornionego amorficznego krzemu (α-Si:H) o zawartości 1 at.% H. Na podstawie niskotemperaturowych badań własności sprężystych i termicznych krzemu amorficznego (α-Si) naparowanego wiązką elektronów wykazaliśmy, że w pewnych warunkach osadzania można wyeliminować TLS w tym układzie tak, że warstwy stają się gęstsze i strukturalnie bardziej uporządkowane. Uzyskane przez nas wyniki wskazują, że TLS nie są nieodłączną cechą stanu szklistego, ale lokują się w regionach o niskim zagęszczeniu sieci amorficznej. Praca niniejsza wyjaśnia, że wodór nie pełni roli w usuwaniu TLS w α-Si:H, jak dotąd sądzono, i wskazuje na idealną czterokrotnie kowalencyjnie związaną amorficzną strukturę jako przyczynę znikania TLS. Nasz wynik potwierdza koncepcję, że z α-Si można wytworzyć “doskonałe szkło” o “podobnych do krystalicznych” właściwościach, oferując w ten sposób zachęcającą możliwość wykorzystania go alternatywnie jako prosty krystaliczny dielektryk w takich aplikacjach jak w nowoczesne urządzenia kwantowe, gdzie TLS są źródłem dyssypacji dekoherencji i szumu 1/f.
Źródło:
Archives of Metallurgy and Materials; 2015, 60, 1; 359-363
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Chaotic states induced by resetting process in Izhikevich neuron model
Autorzy:
Nobukawa, S.
Nishimura, H.
Yamanishi, T.
Liu, J.-Q.
Powiązania:
https://bibliotekanauki.pl/articles/91800.pdf
Data publikacji:
2015
Wydawca:
Społeczna Akademia Nauk w Łodzi. Polskie Towarzystwo Sieci Neuronowych
Tematy:
hybrid neuron model
Izhikevich neuron model
chaotic states
Poincar´e section method
Lyapunov method
hybrydowy model neuronowy
model neuronu Izhikevicha
stany chaotyczne
metoda przekroju Poincarego
metoda Lapunowa
Opis:
Several hybrid neuron models, which combine continuous spike-generation mechanisms and discontinuous resetting process after spiking, have been proposed as a simple transition scheme for membrane potential between spike and hyperpolarization. As one of the hybrid spiking neuron models, Izhikevich neuron model can reproduce major spike patterns observed in the cerebral cortex only by tuning a few parameters and also exhibit chaotic states in specific conditions. However, there are a few studies concerning the chaotic states over a large range of parameters due to the difficulty of dealing with the state dependent jump on the resetting process in this model. In this study, we examine the dependence of the system behavior on the resetting parameters by using Lyapunov exponent with saltation matrix and Poincar´e section methods, and classify the routes to chaos.
Źródło:
Journal of Artificial Intelligence and Soft Computing Research; 2015, 5, 2; 109-119
2083-2567
2449-6499
Pojawia się w:
Journal of Artificial Intelligence and Soft Computing Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Correlation Between Superheated Liquid Fragility And Onset Temperature Of Crystallization For Al-Based Amorphous Alloys
Korelacja między krytycznymi parametrami cieczy i temperaturą początku krystalizacji dla amorficznych stopów na bazie Al
Autorzy:
Guo, J.
Hu, X.
Liu, J.
Feng, T.
Yoon, E. Y.
Kim, H. S.
Powiązania:
https://bibliotekanauki.pl/articles/353707.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
superheated liquid fragility
onset temperature of crystallization
thermal stability
krytyczny parametr cieczy
temperatura początku krystalizacji
stabilność termiczna
Opis:
Amorphous alloys or metallic glasses have attracted significant interest in the materials science and engineering communities due to their unique physical, mechanical, and chemical properties. The viscous flow of amorphous alloys exhibiting high strain rate sensitivity and homogeneous deformation is considered to be an important characteristic in thermoplastic forming processes performed within the supercooled liquid region because it allows superplastic-like deformation behavior. Here, the correlation between the superheated liquid fragility, and the onset temperature of crystallization for Al-based alloys, is investigated. The activation energy for viscous flow of the liquid is also investigated. There is a negative correlation between the parameter of superheated liquid fragility and the onset temperature of crystallization in the same Al-based alloy system. The activation energy decreases as the onset temperature of crystallization increases. This indicates that the stability of a superheated liquid can affect the thermal stability of the amorphous alloy. It also means that a liquid with a large superheated liquid fragility, when rapidly solidified, forms an amorphous alloy with a low thermal stability.
Źródło:
Archives of Metallurgy and Materials; 2015, 60, 2B; 1543-1546
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mitigation scratch on fused silica optics using CO2 laser
Autorzy:
Liu, C.-M.
Yan, Z.-H.
Yang, L.
Jiang, Y.
Zu, X.-T.
Wang, H.-J.
Liao, W.
Yuan, X.-D.
Zheng, W.-G.
Powiązania:
https://bibliotekanauki.pl/articles/174978.pdf
Data publikacji:
2016
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
mitigation
scratch
fused silica
CO2 laser
Opis:
The scratch on a fused silica surface was treated as a chain of connected damage sites and mitigated one after another using CO2 laser irradiation. The optical microscopy image shows that a scratch with the width of about 30 μm and length of several millimeters can be completely mitigated without the formation of debris and bubbles. The mitigated scratch can survive under raster scan laser irradiation with the fluency increased up to 11.0J/cm2 at 3ns and 351nm. On the contrary, the substrate without CO2 laser mitigation is seriously damaged under this irradiation. The light modulation induced by mitigation is much smaller when the scratch is mitigated before being damaged. The light modulation is about 2 when the distance to the mitigated sample is larger than 20cm. The birefringence induced by residual stress in the mitigated scratch is measured. The retardance of the mitigated scratch before being damaged is not visible. Therefore, residual stress in this mitigated scratch before being damaged should be not a critical potential risk in laser damage.
Źródło:
Optica Applicata; 2016, 46, 3; 387-397
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Preliminary results of spatial distribution of uranium and thorium in soil profi les near a uranium industrial site, Guangdong province, China
Autorzy:
Wang, J.
Liu, J.
Chen, Y.
Song, G.
Chen, D.
Xiao, T.
Li, H.
Wang, C.
Jiang, F.
Powiązania:
https://bibliotekanauki.pl/articles/146530.pdf
Data publikacji:
2016
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
spatial distribution
thorium
uranium
U/Th ratio
Opis:
Four soil profiles were collected from locations with different distances (5, 50, 250 and 1000 m) from a uranium mill tailings dam, Guangdong province, China, to investigate the pollution status of the soil in mining/ milling-related areas based on the contents of uranium (U) and thorium (Th), thus to understand the impacts of uranium industrial activities to the surroundings. The U and Th concentrations were determined by inductively coupled plasma mass spectrometry (ICP-MS) after conventional HF-HNO3-HClO4 digestion procedures. The results indicate that the soils within 50 m from uranium tailing were severely contaminated; those in 250 and 1000 m soil samples were observed to be with local background level even though these in 250 m had slightly higher U/Th ratios. Uranium concentrations varied from 5.50 ± 0.27 to 160.55 ± 8.03 mg/kg, with maximum values recorded in an intermediate layer of the 5-m distance soil profile. In comparison, the concentration of Th ranged from 6.02 ± 0.30 to 84.71 ± 4.24 mg/kg, with maximum values observed in the top layer of the 1000-m distance soil profile. The U/Th ratio varied from 0.15 to 11.99 compared with 0.20, 0.22 and 0.26 of the average for Guangdong province, national China and the world, respectively. The mean U/Th of four soil profiles showed a reduction with distance from the uranium mill tailing dam, suggesting the relatively large magnitude of uranium elevation in soils within limited distances.
Źródło:
Nukleonika; 2016, 61, 3; 367-371
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Horizontal transfer and functional evaluation of high pathogenicity islands in Avian Escherichia coli
Autorzy:
Tu, J.
Qi, K.
Song, X.
Xue, T.
Ji, H.
Shao, Y.
Liu, H.
Zhou, X.
Zhu, L.
Powiązania:
https://bibliotekanauki.pl/articles/30119.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Opis:
High pathogenicity islands (HPIs) in Escherichia coli encode genes that are primarily involved in iron uptake and regulation, and confer virulence and pathogenicity. The aim of this study was to investigate the transfer of HPIs in avian E. coli and identify the function of HPI in the acceptor strain. The HPI transfer strain was obtained under conditions of low temperature and low iron abundance, and the donor and acceptor strains were confirmed. E. coli HPIs are transferred by horizontal gene transfer events, which are likely mediated primarily by homologous recombination in HPI-adjacent sequences. Assays for biological activity and pathogenicity changes in the acceptor strain indicated that HPIs might not be involved in pathogenesis in avian E. coli, and thus the main function of HPIs in this strain of bacteria may be to regulate iron nutrition.
Źródło:
Polish Journal of Veterinary Sciences; 2017, 20, 2
1505-1773
Pojawia się w:
Polish Journal of Veterinary Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Path following control of the underactuated USV based on the improved line-of-sight guidance algorithm
Autorzy:
Liu, T.
Dong, Z.
Du, H.
Song, L.
Mao, Y.
Powiązania:
https://bibliotekanauki.pl/articles/259559.pdf
Data publikacji:
2017
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
unmanned surface vessel (USV)
path following control
Serret-Frenet coordinate frame
underactuated system
improved lineof-sight guidance algorithm
nonlinear backstepping method
Opis:
The path following control problem of the underactuated unmanned surface vessel (USV) is studied in this paper. An improved line-of-sight (LOS) guidance algorithm is proposed which can adjust adaptively based on the path following error. The global asymptotically stable path following controller is designed based on the nonlinear backstepping method and the Lyapunov stability theory. Firstly, the USV path following error model is established in the Serret-Frenet (SF) coordinate frame. The path following error in the inertial coordinate frame is transformed into the SF coordinate frame, which is used to define the path following control problem. Secondly, inspired by the traditional LOS guidance algorithm, the longitudinal path following error in the SF coordinate frame is introduced into the improved LOS guidance algorithm. This allows the algorithm to adjust adaptively to the desired path. Thirdly, in order to solve the underactuated problem of the USV path following control system, the tangential velocity of the desired path is designed as a virtual input. The underactuated problem is converted to a virtual fully actuated problem by designing the virtual control law for the tangential velocity. Finally, by combining backstepping design principles and the Lyapunov stability theory, the longitudinal thrust control law and the yaw torque control law are designed for the underactuated USV. Meanwhile, the global asymptotic stability of the path following error is proved. Simulation experiments demonstrate the effectiveness and reliability of the improved LOS guidance algorithm and the path following controller.
Źródło:
Polish Maritime Research; 2017, 1; 3-11
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 24

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