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1
Content available remote Allelopathic interactions between the red-tide causative dinoflagellate Prorocentrum donghaiense and the diatom Phaeodactylum tricornutum
Cai ZH., Zhu H., Duan S.
Oceanologia
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2014
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No. 56 (3)
639--650
EN
The interactions between the red-tide causing dinoflagellate Prorocentrum donghaiense and the marine diatom Phaeodactylum tricornutum were investigated using a co-culture experiment and an enriched culture filtrate experiment. The results showed that when the two microalgae were cultured together with different initial cell densities, the growth of one species was basically suppressed by the other one. In addition, the enriched culture filtrates of one species had generally inhibitory effects on the other one. Our result inferred that P. donghaiense and P. tricornutum would interfere with each other mainly by releasing allelochemicals into the culture medium, and that the degree of allelopathic effects was dependent on the initial cell densities and growth phases. The allelopathic interactions between microalgal species may contribute to the formation and succession of red tides.
2
Content available remote The Research on Effect of Zero Order Holder and First-order Lag to High Performance Digital Arc-welding Power Supply
He L., Duan S.
Przegląd Elektrotechniczny
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2013
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R. 89, nr 1b
243--247
EN
Digital control become more attractive because of their stable control precision and flexible control strategy in welding occasions. In this paper, the impact of zero order holder and first-order lag to system performance is analyzed firstly and it is conclude that zero order holder and first-order lag will reduce the stability of the system. Also, the trend of stability will change with damp PF-FB power supply in both voltage loop control and current loop control. Based on those conclusion, the control parameters are set based on unload state when the system in voltage loop and short-circuit state in current loop, it maximally improves the system steady and dynamic performance, especially, it reduces the excessive short-circuit current. Simulation and experiment verifies the results.
PL
W artykule wykazano, że podtrzymanie zerowego rzędu i opóźnienie pierwszego rzędu ograniczają stabilność układu. Bazując na tym założeniu określono parametry układu sterowania w stanie nieobciążonym oraz właściwości statyczne i dynamiczne, szczególnie w celu redukcji dodatkowego prądu zwarcia.
3
Content available remote Compensatory growth of the bloom-forming dinoflagellate Prorocentrum donghaiense induced by nitrogen stress [commun.]
Cai Z., Duan S., Zhu H.
Oceanologia
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2013
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No. 55 (1)
269-276
EN
Although the phenomenon of compensatory growth has been documented in some animals and higher plants, little information is available on its manifestation in marine microalgae. We have conducted the first study on the compensatory growth of the red tide causative dinoflagellate Prorocentrum donghaiense after its recovery from different nitrogen concentrations. The results showed that NaNO3 concentrations of 0 and 7.5 mg l-1 significantly reduced the growth of P. donghaiense, as compared to 37.5 and 75 mg l-1. When the microalgal cells were returned to 75 mg l-1, they exhibited subsequent compensatory growth. The most significant compensatory growth was found in those cells previously experiencing 0 mg dm3, followed by 7.5 mg dm3, indicating that compensatory growth depended on the extent of nitrogen stress they had been subjected to. Our results suggest that compensatory growth can be induced in the marine microalga P. donghaiense after its recovery from nitrogen fluctuation, and that this should be taken into consideration in the prevalence of P. donghaiense blooms in coastal waters.
4
Content available remote Modeling, Control and Implementation of a Lithium-ion Battery Charger in Electric Vehicle Application
Hu G., Duan S., Cai T., Liu B.
Przegląd Elektrotechniczny
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2012
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R. 88, nr 1b
255-258
EN
The rapid development of Electric Vehicle powered by lithium-ion battery has resulted in significant interesting to charging device. However, the nonlinear characteristics of lithium-ion battery increase the complexity of charger designing. In this paper, to overcome the disadvantages, battery model is established and its parameters are evaluated adopted an exponential fitting method. Then an appropriate control strategy is proposed based on small signal model to realize the proposed charging strategy. Finally, experimental results from a laboratory prototype are shown to verify the feasibility of the proposed strategies.
PL
W pracy przedstawiono układ ładowania baterii litowych stosowanych w pojazdach elektrycznych. Problemem jest nieliniowa charakterystyka baterii dlatego układ musi mieć odpowiedni system sterowania zapewniający właściwą strategię ładowania.
5
Content available remote An Improved Double Closed Loop Control Strategy for Air Plasma Cutting Converter
Liu B., Duan S., Li X.
Przegląd Elektrotechniczny
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2012
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R. 88, nr 2
278-282
EN
A double closed loop control strategy composed of inner voltage-loop and external current-loop with a current-reference feedforward link was proposed based on the output characteristic of an air plasma cutting converter(APCC) with non-contact arc ignition. An equivalent mathematical model of the APCC was presented and a controller was designed via frequency domain analysis. Experiments verified that the proposed control strategy showed excellent dynamic and static performance, which significantly improved the arc ignition and the robustness against load disturbance.
PL
Przedstawiono strategię sterowania konwertera do cięcia plazmowego z podwójną pętlą złożoną z wewnętrznej pętli napięcia i zewnętrznej prądowej. Przedstawiono model matematyczny i projekt z analizą w domenie częstotliwości. Obiekt sprawdzono eksperymentalnie.
6
Content available remote Research on excitation control system of multi-functional flexible power conditioner
Chen Z., Zou X., Duan S., Wei H.
Przegląd Elektrotechniczny
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2011
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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.
7
Content available remote Application of flywheel energy storage to damp power system oscillations
Chen Z., Zou X., Duan S., Wen J., Cheng S.
Przegląd Elektrotechniczny
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2011
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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.
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