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1

Effects of CO2 Fumigation and Nitrogen Addition on Soil Respiration in a Wetland Ecosystem : Experimental Approach with Top Open Chambers

Wang J., Fu X., Wang J., Zhong H., Zhang R., Ni H.

Polish Journal of Ecology

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2018

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Vol. 66, nr 2

102--113

EN

Soil respiration plays a crucial role in global carbon cycling of terrestrial ecosystems. Changes in atmospheric CO2 and nitrogen (N) addition across the globe are likely to affect soil respiration. However, the effects of elevated CO2, and N addition on soil respiration are not fully understood especially in wetland ecosystems. To evaluate the effects of atmospheric CO2 and N availability on soil respiration, a paired, nested manipulative in situ experiment was performed, using CO2 fumigation within Open-Top Chambers as the primary factor, and N (as NH4NO3) as the secondary factor in a temperate wetland in northeastern China in 2010 and 2011. CO2 fumigation significantly enhanced soil respiration, according to repeated-measures ANOVA, and the stimulatory effect of CO2 fumigation on soil respiration was sustained during the whole experimental period regardless of N addition. However, the positive soil respiration effect of N addition alone weakened over time. Moreover, there was a significant interaction between CO2 fumigation and N addition. Soil temperature explained 50-66% of the variation in soil respiration. Moreover, soil respiration was positively correlated with the root N content and litter decomposition rate. The results suggested that elevated CO2 concentrations will accelerate soil respiration and ecosystem carbon cycling, thus, limiting soil carbon sequestration, especially when coupled with increasing N deposition.

2

Process improvement and kinetic study on copper leaching from low-grade cuprite ores

Bai S., Fu X., Li C., Wen S.

Physicochemical Problems of Mineral Processing

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2018

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Vol. 54, iss. 2

300--310

EN

Process improvement and kinetic study on copper leaching from low-grade cuprite ores in sulfuric acid solution are presented in this paper. Effects of major leaching parameters on copper leaching efficiency are determined. The results indicate that copper minerals in the raw ores are mainly cuprites. The reaction rate of this ore increases with an increase in temperature, reaction time, sulfuric acid concentrations and decrease in the particle size of ore. Leaching of about 92.5% of copper is achieved using 0.125-0.074 mm ore particle size at a reaction temperature of 353 K for 180 min reaction time with 150 g/dm3 sulfuric acid. The solid/liquid ratio was maintained constant at 1:15. Leaching kinetic indicates experimental data complies with shrinking core mode (SCM). It is found in the study that agitation rate is not an influential factor on leaching rate and that the dissolution rate is controlled by surface chemical reaction. The average activation energy of the process is determined to be 45.28 kJ mol-1, and the reaction order of H2SO4 is 0.8093.

3

Mechanism and Kinetics Studies on Non-Isothermal Decomposition of Ludwigite in Inert Atmosphere

Fu X., Chu M., Gao L., Liu Z.

Archives of Metallurgy and Materials

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2018

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Vol. 63, iss. 3

1217--1224

EN

Ludwigite is the main available boron-bearing resource in China. In order to enrich the theory system and optimize its utilization processes, this paper study the mechanism and kinetics on non-isothermal decomposition of ludwigite in inert atmosphere by means of thermal analysis. Results show that, the decomposition of serpentine and szajbelyite is the main cause of mass loss in the process. At the end of decomposition, hortonolite and ludwigite are the two main phases in the sample. The average E value of structural water decomposition is 277.97 kJ/mol based on FWO method (277.17 kJ/mol based on KAS method). The results is proved to be accurate and reliable. The mechanism model function of structural water decomposition is confirmed by Satava method and Popescu method. The form of the most probable model function is G(α) = (1 – α)–1– 1 (integral form) and f (α) = (1 – α)2 (differential form), and its mechanism is chemical reaction. This is verified by the criterion based on activation energy of model-free kinetics analysis.

4

Microstructure and Mechanical Properties of Duplex Structured Mg-Li-Zn-Y Alloys

Su J., Yang Y., Fu X., Ma Q., Ren F., Peng X.

Archives of Foundry Engineering

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2018

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Vol. 18, iss. 1

181--185

EN

As-cast Mg-6Li-0.3Zn-0.6Y and Mg-6Li-1.2Zn-1.2Y (wt%) alloys were prepared and extruded at 260 ºC with an extrusion ratio of 25. The microstructure and mechanical behavior of as-cast and extruded alloys are reported and discussed. The results show that Mg-6Li-1.2Zn- 1.2Y alloy is composed of α-Mg, β-Li, and W-Mg3Zn3Y2 phases while Mg-6Li-0.3Zn-0.6Y alloy contains α-Mg, β-Li, W-Mg3Zn3Y2 phase and X-Mg12ZnY. After hot extrusion, the microstructure of specimens is refined and the average grains size of extruded alloys is 15 μm. Dynamic recrystallization occurs during the extrusion, leading to grain refinement of test alloys. Both the strength and elongation of test alloys are improved by extrusion. The extruded Mg-6Li-0.3Zn-0.6Y alloy possesses an ultimate strength of 225 MPa with an elongation of 18% while the strength and elongation of Mg-6Li-1.2Zn-1.2Y alloy are 206 MPa and 28%, respectively. The X-phase in Mg-6Li-0.3Zn- 0.6Y is beneficial to the improvement of strength, but will lead to the decrease of ductility.

5

Thermal Decomposition Characteristics of Ammonium Nitrate(V) in the Presence of Mn2O3/Graphene Oxides

Xu Z., Xu G., Fu X., Wang Q.

Central European Journal of Energetic Materials

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2017

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Vol. 14, no. 3

636--659

EN

Nano-composites (Mn2O3, Mn2O3/graphene oxides (GO)) were prepared by a new method. The nano-composites were characterized by XRD and HRTEM. The catalytic performance of the nano-composites on the thermal decomposition of ammonium nitrate(V) (AN) was investigated by TG-DSC and TG-MS. The reaction of AN with the nano-composites in the condensed phase was investigated by RSFTIR. The results of TG-DSC experiments indicated that the nano-composites significantly catalyze the thermal decomposition of AN, especial Mn2O3/GO. The exothermic reaction of AN with Mn2O3/GO commenced at about 185 °C. Based on the TG-MS results, it was ascribed to N2O formation. In the RSFTIR experiments, the dissociation reaction and ionization reaction of AN were both detected. NOx formation at low temperature was also found. NH2 was directly oxidized by HNO3/NO3− at low temperature. The interaction between Mn2O3 and NH3 was detected according to DRIFT experiments. At elevated temperature, the functional groups of GO are destroyed, which had an influence on the interaction between Mn2O3 and GO. A probable mechanism for the exothermic reaction and then its disappearance is proposed. HNO3 gas was absorbed on the surface of solid AN, which can markedly catalyze the thermal decomposition of AN. Perhaps the HNO3 plays a key role in the exothermic reaction and then the reaction of AN disappears at very low temperatures.

6

Microstructure and Mechanical Behavior of Mg-0.5Si-xSn Alloys

Fu X., Yang Y., Ma Q. Y., Peng X., Xu T.

Archives of Foundry Engineering

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2017

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Vol. 17, iss. 4

179--184

EN

Mg-0.5Si-xSn (x=0.95, 2.9, 5.02wt.%) alloys were cast and extruded at 593K (320 ºC) with an extrusion ratio of 25. The microstructure and mechanical properties of as-cast and extruded test alloys were investigated by OM, SEM, XRD and tensile tests. The experimental results indicate that the microstructure of the Mg-0.5Si-xSn alloys consists of primary α-Mg dendrites and an interdendritic eutectic containing α-Mg, Mg2Si and Mg2Sn. There is no coarse primary Mg2Si phase in the test alloys due to low Si content. With the increase in the Sn content, the Mg2Si phase was refined. The shape of Mg2Si phase was changed from branch to short bar, and the size of them were reduced. The ultimate tensile strength and yield strength of Mg-0.52Si-2.9Sn alloy at the temperature of 473K (200 ºC) reach 133MPa and 112MPa respectively. Refined eutectic Mg2Si phase and dispersed Mg2Sn phase with good elevated temperature stability are beneficial to improve the elevated temperature performance of the alloys. However, with the excess addition of Sn, large block-like Mg2Sn appears around the grain boundary leading to lower mechanical properties.

7

Vertical distribution of nearshore flow velocity

Li Ch., Fu X., Li R., Dai L., Chen P.

Polish Maritime Research

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2016

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S 1

104--108

EN

In this paper, a new exponential formed vertical distribution of nearshore flow velocity is constructed, which is simpler in form and more suitable for engineering application. The physical meaning of the new formula is more specific than that of Soulsby. Compared with those logarithmic formed ones, the new one does not need the maximum velocity and only needs the mean velocity in vertical, which gives it better engineering practicability. Apply the new formula to Jiangsu coastal area and compare the results with that of Soulsby whose results show the new formula agrees better with the measured flow velocity, which reasonably reflects the basic principles of vertical distribution of flow velocity.

8

Correction of sample-time error for time-interleaved sampling system using cubic spline interpolation

Qin G., Liu G., Gao M., Fu X., Xu P.

Metrology and Measurement Systems

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2014

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Vol. 21, nr 3

485--496

EN

Sample-time errors can greatly degrade the dynamic range of a time-interleaved sampling system. In this paper, a novel correction technique employing a cubic spline interpolation is proposed for inter-channel sample-time error compensation. The cubic spline interpolation compensation filter is developed in the form of a finite-impulse response (FIR) filter structure. The correction method of the interpolation compensation filter coefficients is deduced. A 4GS/s two-channel, time-interleaved ADC prototype system has been implemented to evaluate the performance of the technique. The experimental results showed that the correction technique is effective to attenuate the spurious spurs and improve the dynamic performance of the system.

9

The D e (T, t) plot: A straightforward self-diagnose tool for post-IR IRSL dating procedures

Fu X.

Geochronometria

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2014

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Vol. 41, no. 4

315--326

EN

This study presents a new self-diagnose method for the recently developed post-IR infrared stimulated luminescence (pIRIR) dating protocols. This criterion studies the dependence of equivalent dose (D e) on measurement-temperature (T) and time (t), by applying the D e (t) analysis to the IRLS and pIRIR signals measured under different temperatures, and combines these D e (t) plots into one, so-called the D e (T, t) plot. The pattern of the D e (T, t) plot is shown to be affected by anomalous fading, partial bleaching and non-bleachable signal. A D e plateau can be achieved in the D e (T, t) plot only when the effects of these factors are insignificant. Therefore, this plot can be used as a self-diagnose tool for the validity of pIRIR results. The D e (T, t) analysis has been applied to four recently developed pIRIR protocols, using aeolian samples with different ages. The results show that this self-diagnose tool can be applied to different pIRIR protocols for validating the pIRIR dating results and evaluating the pIRIR measurement conditions.

10

Soft-switching AC module inverter with flyback transformer for photovoltaic power system

Tan G., Tang Y., Gao B., Fu X., Ji Y.

Przegląd Elektrotechniczny

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2012

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R. 88, nr 10a

180-184

EN

This paper presents an AC module inverter for photovoltaic (PV) power system. The PV inverter employs a Buck-Boost converter on the DC side and a flyback inverter on the AC side. Based on capacitive idling (CI) techniques and peak current control method, the proposed inverter shows low current distortion, high power factor, small power decoupling capacitor and soft-switching operation. Analysis and experimental results are provided to demonstrate these excellent features.

PL

W artykule zaprezentowano modułowy przekształtnik AC zastosowany w systemach fotowoltaicznych. Przekształtnik wykorzystuje konwerter Buck-Boost po stronie DC i konwerter typu flyback po stronie AC. Układ bazuje na jałowym biegu pojemnościowym i kontroli wartości szczytowej prądu. (Modułowy przekształtnik AC z transformatorem typy flyback w systemie fotowoltaicznym)

11

Interference effect in a dual microresonator-coupled Mach-Zehnder interferometer

Lu Y., Huang X., Fu X., Wen W., Yao J.

Optica Applicata

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2012

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Vol. 42, nr 1

23-29

EN

We present a theoretical study of interference effect in a Mach-Zehnder interferometer in which two microresonators are side coupled to both arms of the interferometer. The results show that sharp asymmetric Fano resonance, coupled resonator induced transparency and absorption effects can be created in such a structure. We demonstrate that these effects arise from interference between a resonance mode and a continuing propagating mode with asymmetric phase difference, destructive interference between two overcoupled resonance modes, and constructive interference between an overcoupled resonance mode and an undercoupled mode or a continuing propagating mode with symmetric phase differences, respectively. These effects may offer a better understanding of the analogous effects in atomic medium and also make optical resonators a potential device to utilize these effects.

12

Surface plasmon resonance sensor based on photonic crystal fiber filled with silver nanowires

Fu X., Lu Y., Huang X., Hao C., Wu B., Yao J.

Optica Applicata

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2011

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Vol. 41, nr 4

941--951

EN

Silver nanowire filled photonic crystal fibers are proposed in this paper to achieve surface plasmon resonance sensors and overcome the complicacy and difficulty of coating the holes in the photonic crystal fiber. Optical field distributions of these fibers at different wavelengths are calculated and simulated using the finite element method (FEM), and the sensing properties are discussed in both areas of resonant wavelength and intensity detection. Numerical simulation results show that carefully designed structure of the sensor brings about an excellent effect, with both spectral and intensity sensitivity in the range of 4×10-5-5×10-5 RIU, better than in the case of similar structures coated with metal film, and the fabrication is expected to be simplified.

13

Integrated software tools supporting decision making on identification, prediction and optimization of complex technical systems operation, reliability and safety. Part 3. Integrated software tools application – Exemplary system operation and reliability characteristics prediction

Blokus-Roszkowska A., Kołowrocki K., Fu X.

Journal of Polish Safety and Reliability Association

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2011

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Vol. 2, No. 2

289--296

EN

There is presented the application of the integrated software tools to the operation and reliability of an exemplary complex technical system prediction. The computer program CP 8.5 is used to determine the unconditional mean sojourn times and the limit transient probabilities of the exemplary system operation process at the particular operation states evaluations. Using the computer program CP 8.6 there are performed the evaluations of the exemplary system unconditional multistate reliability function, the expected values and the standard deviations of its unconditional lifetimes in the reliability state subsets and the mean values of its lifetimes in the particular reliability states. Finally, in the case when the system is repairable, its renewal and availability characteristics are estimated from the results of computer program CP 8.8.

14

Integrated software tools supporting decision making on identification, prediction and optimization of complex technical systems operation, reliability and safety. Part 1. Integrated software tools description

Blokus-Roszkowska A., Kołowrocki K., Fu X.

Journal of Polish Safety and Reliability Association

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2011

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Vol. 2, No. 2

267--278

EN

The paper is composed of six parts and presents the software tools created in the scope of the Poland-Singapore Joint Research Project, the Integrated Safety and Reliability Decision Support System – IS&RDSS. In the paper first part, there are briefly described all computer programs with pointed aims. Dependencies between computer programs and possible transitions using this integrated package of software tools are presented at the scheme algorithm. In the remaining paper parts, there is presented the application of the computer programs, being in the package of software tools, to the reliability analysis of an exemplary complex technical system.

15

Integrated software tools supporting decision making on identification, prediction and optimization of complex technical systems operation, reliability and safety. Part 2. Integrated software tools application – Exemplary system operation and reliability unknown parameters identification

Blokus-Roszkowska A., Kołowrocki K., Fu X.

Journal of Polish Safety and Reliability Association

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2011

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Vol. 2, No. 2

279--288

EN

There is presented the application of the integrated software tools to the operation and reliability models of an exemplary complex technical system unknown parameters identification. There are performed in the paper, the exemplary system operation and reliability analysis and modelling. The identification of the probabilities of transitions this system operation process between the operation states and the conditional mean values of this process sojourn times at the particular operation states because of the lack of statistical data is performed throw the arbitrary fixing their values assumption. Next using the computer program CP 8.3 the automatic evaluation of the system components unknown intensities of departures the reliability state subsets and the identification of the exponential forms of their multistate reliability functions on the arbitrarily fixed statistical data coming from the system components states changing processes are performed as well.

16

A study on temperature characteristics of green silicon photodetector

Fu X., Yao S., Tao G., De M.

Optica Applicata

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2010

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Vol. 40, nr 4

935--941

EN

Green silicon photodetector is successfully developed on the substrate of n-type single-crystal (100) silicon. To improve its performance, the detector is optimized by optimizing the p-n junction depth xj and the thickness of antireflection layer to reduce dark current, shorten response time and increase sensitivity. The spectrum response SNR can be over 104 within the wavelength range of 500-600 nm and the peak of spectral responsivity is 0.48 A/W at about 520 nm. The temperature characteristics of the dark current at reverse bias and photocurrent at zero bias are emphatically investigated. Firstly, the temperature behavior of dark current at 10 V reverse bias voltage and temperature range of 253-323 K is studied. Results show that dark current is dominated by generation-recombination current Igr the temperature range of 253-283 K and it is dominated by traps tunneling current Itt at the temperature range of 283-323 K. Secondly, the temperature behavior of photocurrent at zero bias and temperature range of 213-353 K is discussed. Results show that photocurrent increases as temperature increases below room temperature and almost holds the line over room temperature. Consequently, photodetector fulfils quality requirements.

17

The effect of aging process on the formation of carbonate particles during preparation of overbased calcium alkylsalicylates

Fu X., Liu Y., Yao W.

Tribologia

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2003

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nr 2

11--18

EN

The carbonation process is generally considered as the most important stage to form nano-carbonate particles during the preparation of overbased calcium alkylsalicylates while the aging stage has not been emphasized by the researchers. This paper had studied the influence of aging process on the TBN (Total Basicity Number) values of overbased products and the micelle structure of carbonate particles during preparing overbased calcium alkylsalicylate by the freeze-etching microscopic observation and calcium distribution measurement method. The results showed that TBN increased as the aging time lasted and remained the stable at about 3.0 hours. The diameter of carbonate particles became smaller and well-distributed after the aging process. Water and methanol had played an important role in the re-formation of the carbonate particles during the aging process, the mechanism on the aging process had been discussed.

PL

Autorzy przedyskutowali mechanizmy procesu starzenia alkilosalicylanów wapnia, które dotychczas nie byty rozważane, a także zbadali wpływ procesu starzenia na wartość liczby zasadowej (TBN) produktów o odczynie zasadowym. Stwierdzono, że liczba zasadowa zwiększała się w miarę upływu czasu starzenia, by ustabilizować się po upływie 3 godzin. Zbadano także budowę miceli cząstek węglanów w czasie wytwarzania alkilosalicylanów wapnia. Użyto do tego obserwacji mikroskopowych zamrożonych próbek oraz metody oceny zawartości wapnia.

18

An investigation of the reaction process of super - overbased calcium alkyl-salicylate

Liu Y., Fu X., Liu W., Fu X.

Tribologia

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1999

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nr 3

247-255

EN

The Changes of components and size of colloidal particles of super-overbased calcium alkyl-salicylate during the reaction process were studied with freeze - etching electron microscopic FT-IR.The results show that the size of colloidal particles decrease gradually and the content of calcium hydroxide in colloidal particles increase with the Total Basicity Number (TBN) of the products increase.A model described the reaction process of neutralizatio and carbonation of overbased calcium alkyl-salicylate is suggested.

PL

Badano zmiany składu i rozmiarów cząstek koloidalnych supernadzasadowego alkilosalicynianu wapnia podczas procesu reakcyjnego, za pomocą FE-EM i FTIR. Na podstawie uzyskanych wyników stwierdzono, że wielkość cząstek koloidalnych stopniowo maleje, a zawartość wodorotlenku wapnia w cząstkach koloidalnych wzrasta wraz ze wzrostem liczby zasadowej (TBN) produktów. Zaproponowano model procesu reakcyjnego neutralizacji i nasycania dwutlenkiem węgla supernadzasadowego alkilosalicynianu wapnia.