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Potholes of Mountain River as Biodiversity Spots : Structure and Dynamics of the Benthic Invertebrate Community

Ren H., Yuan X., Yue J., Wang X., Liu H.

Polish Journal of Ecology

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2016

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Vol. 64, nr 1

70--83

EN

Temporary freshwater rock pools, as special, small-sized and isolated habitats, provide ideal systems for studying island biogeography and ecological theories and processes. In this study, a total of 70 potholes of mountain rivers were sampled during the four seasons from November 2013 to October 2014 to assess the structure of the benthic invertebrate community and to identify the relationships between habitat characteristics and the community composition. Pothole area ranged from approximately 0.01 to 0.39 m2, and pothole depth ranged from 0.03 to 0.74 m. Forty-three taxa belonging to 37 families and 16 orders were collected from the potholes. The highest numbers of benthic invertebrate taxa were observed in summer and the highest average number of taxa per pothole (8.5) was observed in autumn. The diversity was the highest in spring, and the average densities of benthic invertebrates were highest in autumn. Large potholes supported more taxa than small ones and significant relationships between richness and pothole area, richness and water volume were observed. The results of Redundancy Analysis show that the community composition of benthic invertebrates in the potholes was closely correlated with water temperature, pothole area and water depth. Our results indicate that benthic invertebrate communities in river potholes are mainly structured by water depth, pothole area and water volume. The seasonal changes are also an important factor determining the presence/absence of certain taxa.

2

Research on Grid-Connected Photovoltaic System Based on Improved Algorithm

Cai W., Ren H.

Przegląd Elektrotechniczny

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2012

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R. 88, nr 3b

22-25

EN

In order to simulate and predict the behaviors of the real photovoltaic system, this paper develops a grid-connected photovoltaic simulation system with maximum power point tracking (MPPT) function using MATLAB software. An engineering model for the photovoltaic (PV) cell is first established and then combined with the models of an MPPT controller and a DC-DC converter. This paper uses an improved algorithm in the MPPT controller by comparing with the commonly-used algorithms. A DC-AC inverter using double closed loop control method is used to track the grid characteristics. The simulation results show that the system not only achieves the maximum power point tracking function quickly but also modulates the outputs of the inverter into sine waveforms accompanied with fewer ripples. And the power factor is close to 1.

PL

W artykule zaproponowano symulację połączonego sieciowo system fotowoltaicznego z funkcja śledzenia maksymalnej mocy. Zaproponowano model inżynierski w MATLABie złożony ze sterownika i przekształtnika. Przekształtnik DC-AC wykorzystuje podwójną zamkniętą pętlę sterowania.

3

Preparation and Characterization of Desensitized ?-HNIW in Solvent-Antisolvent Recrystallizations

Jiang X., Guo X., Ren H., Jiao Q.

Central European Journal of Energetic Materials

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2012

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Vol. 9, nr 3

219-236

EN

The solubility of hexanitrohexaazaisowurtzitane (HNIW) in solvent and solvent-antisolvent mixtures, and the temperature at which the HNIW's polymorph transforms were studied. The solubility of HNIW in solvent-antisolvent mixtures was measured at 30 C and these data were fitted to a generalized solubility curve. Recrystallization experiments were conducted at 30 C in the case of saturation with the volume ratio of ethyl acetate to petroleum ether (chloroform) ranging from 0:1 to 4:1. Desensitized HNIW was obtained by ethyl acetate and petroleum ether crystallization and characterized by Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), High Performance Liquid Chromatography (HPLC) and Scanning Electron Microscopy (SEM). The FTIR and XRD spectra confirmed the structural features of ε-HNIW. The blocklike ε-HNIW grains had an average particle size of 160 ?m and high purity (98.52%). The decomposition of ε-HNIW was observed in the temperature range of 225-246 C by Differential Scanning Calorimetry (DSC). Furthermore, the impact and friction sensitivity tests suggested that the desensitized ε-HNIW was less sensitive than raw HNIW. Small scale gap tests with desensitized ε-HNIW showed that these crystals are less sensitive to shock initiation.