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1
Content available remote Research on excitation control system of multi-functional flexible power conditioner
100%
Chen Z. , Zou X. , Duan S. , Wei H.
Przegląd Elektrotechniczny
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2011
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tom R. 87, nr 4
172-175
EN
A new kind of FACTS equipment, the multi-functional Flexible Power Conditioner (FPC), is proposed in this paper. The proposed equipment makes use of an advanced synchronous condenser and a flywheel with an AC excitation and vector control technology based power electronics device. It can perform multi--functions including energy storage, active and reactive power generation when used in power systems to enhance the stability of it. A 10kVA excitation control system of FPC was developed. Based on the analysis of control strategy, the start, steady and dynamic performances are studied experimentally. Experimental results show that soft start and various operation states can be implemented. And the excitation control system can be applied to flywheel type FPC system.
PL
Zaproponowano nowy rodzaj urządzenia FACTS - wielofunkcyjny, elastyczny kondycjoner mocy FPC. Kondycjoner wykorzystuje koło zamachowe jako zasobnik energii. Urządzenie umożliwia magazynowanie energii, generację bierną lub czynną do poprawy stabilności systemu. Opracowano system sterowania o mocy 10 kVA. Start, ciągła praca i właściwości dynamiczne systemu były analizowane eksperymentalnie.
2
Content available Experimental study of a small gas-puff Z-pinch device
100%
Luo C. , Wang X. , Zou X.
Nukleonika
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2006
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tom Vol. 51, nr 1
43-46
EN
A small gas puff Z-pinch device has been constructed and operated. The device has the parameters: the capacitance of energy storage capacitors 16 mi F, charging voltage 22 kV, peak current 210 kA and a quarter of current period 2.4 mi s. A three-frame Mach-Zehnder interferometer and a compact Thomson ion energy analyzer were developed for Z-pinch plasma experiment. According to the results of diagnostics, the electron density ne of the plasma right before pinch instant is larger than 5.4 × 1019/cm3, the corresponding pinch velocity v of the plasma sheath is 9.0 cm/ěs. Clear parabolas produced by neon ions Ne+, Ne2+, Ne3+ and Ne4+ on CR-39 target have been observed. The energy spectra dN/dTdů for Ne+, Ne2+, Ne3+ and Ne4+ ions were determined. The highest energies of Ne+, Ne2+, Ne3+ and Ne4+ ions emitted from our Z-pinch plasma are below 1.3 MeV.
3
Content available remote Speech Enhancement by Short-Time Spectrum Estimation with Multivariate Laplace Speech Model
100%
Zhou B. , Zhang X. , Zou X. , Zhao G.
Przegląd Elektrotechniczny
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2012
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tom R. 88, nr 12a
338-342
EN
The paper presents a new short-time spectrum estimation algorithm for speech enhancement. A novel multivariate Laplace speech model is utilized to characterize the dependencies between adjacent DFT coefficients of speech, based on which a minimum mean-square error (MMSE) estimator of speech spectral components is derived. Moreover, the speech presence uncertainty is incorporated to modify the MMSE estimator. Experimental results show that the developed algorithm achieves better noise suppression and lower speech distortion compared to the existing speech enhancement methods.
PL
W artykule przedstawiono nowy algorytm estymacji krótkookresowego spektrum głosu do poprawy dźwięku mowy. Wykorzystano wieloczynnikowy model Laplace'a w celu scharakteryzowania zależności pomiędzy składnikami DFT dźwięku mowy. Na tej podstawie obliczane jest minimum błędu średnio-kwadratowego dla estymatora. Wyniki eksperymentalne potwierdzają ulepszoną skuteczność eliminacji zakłóceń mowy, w porównaniu ze stosowanymi metodami.
4
Ethanol content in plants of Brassica napus L. correlated with waterlogging tolerance index and regulated by lactate dehydrogenase and citrate synthase
100%
Xu B. , Cheng Y. , Zou X. , Zhang X.
Acta Physiologiae Plantarum
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2016
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tom 38
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nr 03
5
Content available Simultaneous extraction of vanadium and chromium from vanadium slag using low-pressure liquid phase oxidation method
88%
Xia J.-P. , Zheng S.-L. , Wang S.-N. , Liu B. , Zou X.
Physicochemical Problems of Mineral Processing
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2018
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tom Vol. 54, iss. 2
609--619
EN
A low-pressure liquid oxidation method was proposed and proven to be effective to extract vanadium and chromium simultaneously from the vanadium slag in concentrated NaOH aqueous solutions. The effect of temperature, NaOH mass concentration, liquid-to-solid mass ratio, stirring speed and pressure on the extraction of vanadium and chromium in NaOH aqueous solutions were systematically investigated. Under the optimal reaction conditions (temperature of 473 K, liquid-to-solid mass ratio of 6:1, stirring speed of 700 rpm, NaOH mass concentration of 50%, pressure of 1 MPa and reaction time of 180 min), the vanadium and chromium recovery reached 95% and 90%, respectively. It was found that the reaction temperature and NaOH concentration were important factors for the extraction of vanadium and chromium. The kinetics of the decomposition of vanadium slag in concentrated NaOH aqueous under low pressure was analyzed using the shrinking core model, and the results indicated that the extraction of vanadium and chromium were both governed by the internal diffusion step, with apparent activation energies calculated to be 26.22 and 32.79 kJ/mol, respectively.
6
Content available remote Application of flywheel energy storage to damp power system oscillations
88%
Chen Z. , Zou X. , Duan S. , Wen J. , Cheng S.
Przegląd Elektrotechniczny
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2011
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tom R. 87, nr 3
333-337
EN
Flywheel energy storage system (FESS) is believed to be a potential solution for power quality improvements. This paper proposed a new idea of using a large-mass varying-speed flywheel as an energy storage element to damping power system electromechanical oscillations. In the paper, the FESS is studied in the context of a single-machine infinite-bus (SMIB) power system. The mathematical model of the SMIB power system including a FESS is established, and the Phillips-Heffron controI structure of the power system is described. Based on the principle of the complex torque coefficient (CTC) method, the expression of the complex electromagnetic torque of the entire power system inctuding the FESS unit is derived. A 10 kW prototype of FESS, which consists of a double-fed induction machine (DFIM) and a voltage-source pulse width modulation (PWM) rectifier-inverter used as an AC exciter, is developed. Simulation and experiment results demonstrate that it is effective in damping the power system oscillations.
PL
System magazynowania energii typu FESS (z kołem zamachowym) może być potencjalnym rozwiązaniem problemu poprawy jakości energii. Artykuł omawia zastosowanie systemu FESS do tłumienia oscylacji w systemach mocy. Przedstawiono model matematyczny systemu ze strukturą sterowania typu Philips-Heffron. Bazując na metodzie współczynnika momentu wyprowadzono model momentu elektromagnetycznego w systemie mocy. Zabadano model prototypu 10 KW z podwójnie zasilaną maszyną indukcyjną i żródłem napięcia typu PWM. Symulacje i eksperymenty potiwrdziły zdolnosć tłumienia oscylacji.
7
High flocculation of coal washing wastewater using a novel bioflocculant from Isaria cicadae GZU6722
63%
Zou X. , Sun J. , Li J. , Ila Y. , Xiao T. , Meng F. , Wang M. , Ning Z.
Polish Journal of Microbiology
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2020
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tom 69
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nr 1
8
Exogenous melatonin alleviates damage from drought stress in Brassica napus L. (rapeseed) seedlings
63%
Li J. , Zeng L. , Cheng Y. , Lu G. , Fu G. , Ma H. , Liu Q. , Zhang X. , Zou X. , Li C.
Acta Physiologiae Plantarum
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2018
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tom 40
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nr 03
9
Vital staining of bacteria by sunset yellow pigment
63%
Gao P. , Sun C. , Li Y. , Zou X. , Wu X. , Ling Y. , Luan C. , Chen H.
Polish Journal of Microbiology
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2017
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tom 66
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nr 1
EN
In this study, we describe a method for discriminating pathogenic bacteria with a dye. First, we determined that among several colours tested, the sunset yellow pigment easily coloured Escherichia coli bacteria yellow. Next, we demonstrated that E. coli O157:H7, Shigella flexneri O301, Staphylococcus aureus and Bacillus subtilis could all be well marked by sunset yellow pigment. Finally, we performed bacterial viability assays and found there was no effect on bacterial growth when in co-culture with sunset yellow. Our results suggest that sunset yellow is suitable pigment to dye microorganisms.
10
Isolation and expression pattern of RGS21 gene, a novel RGS member
63%
Li X. , Chen L. , Ji C. , Liu B. , Gu J. , Xu J. , Zou X. , Gu S. , Mao Y.
Acta Biochimica Polonica
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2005
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tom 52
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nr 4
EN
Regulators of G-protein signaling (RGS) proteins are known for the RGS domain that is composed of a conserved stretch of 120 amino acids, which binds directly to activated G-protein α subunits and acts as a GTPase-activating protein (GAP), leading to their deactivation and termination of downstream signals. In this study, a novel human RGS cDNA (RGS21), 1795 bp long and encoding a 152-amino acid polypeptide, was isolated by large-scale sequencing analysis of a human fetal brain cDNA library. Unlike other RGS family members, RGS21 gene has no additional domain/motif and may represent the smallest known member of RGS family. It may belong to the B/R4 subfamily, which suggests that it may serve exclusively as a negative regulator of αi/o family members and/or αq/11. PCR analysis showed that RGS21 mRNA was expressed ubiquitously in the 16 tissues examined, implying general physiological roles.
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