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Temporal characteristics detection and attribution analysis of hydrological time-series variation in the seagoing river of southern China under environmental change

Chen L., Wang Y., Touati B., Guan H., Leng G, Liu W., Lv S., Huang S., Pan Z.

Acta Geophysica

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2018

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Vol. 66, no. 5

1151--1170

EN

Environmental changes have led to a growing conflict between water supply and demand in Qinjiang River. This paper used the data of monthly rainfall, runoff, evaporation and air temperature during the period from 1956 to 2016 and combined 3-year running mean, linear regression method, Mann–Kendall test and R/S analysis method to analyze the change trend of each factor, combined Mann–Kendall test, cumulative anomaly method and slide t test to analyze the variation of each factor and combined Morlet continuous wavelet analysis to identify periodic oscillations. In this paper, the influences of climate change and human activities on the runoff of the Qinjiang River were qualitatively assessed from the aspects of trend, variation and periodicity and the contributions of climate change and human activities to runoff reduction were quantitatively assessed using evaporation difference method and an improved comparative method of the slope changing ratio of cumulative quantity (SCRCQ).The following results were obtained: (1) From 1956 to 2016, the rainfall showed a weak increasing trend, whereas the runoff depth and the evaporation exhibited significant decreasing trend and the air temperature exhibited a significant increasing trend. The rainfall and air temperature will continuously increase, whereas runoff and evaporation will continuously decrease in the future. (2) Rainfall exhibited no significant variation, whereas there were two variation points (1986 and 2003) in the runoff, three variation points (1974, 1986 and 2011) in evaporation and one variation point (1996) in air temperature. (3) Features of rainfall exhibited similarities to periodic changes in runoff, whereas rainfall exhibited significant difference with evaporation and air temperature. (4) Human activities contributed mainly to the runoff reduction. The contribution of human activities to runoff reduction increased from 43.78 to 61.17% in BR period (1983–2003) and increased from 61.17 to 72.66% in CR period (2004–2016). This indicated that the contribution of human activities to runoff reduction increased continuously. The impact of human activities on the reduction in runoff in the Qinjiang River Basin is mainly due to the irrigation, industrial and urban residents’ water use, which is caused by the growth of population and the growth of economic index.

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Effects of Magnesium Powder on the Radiation Characteristics of MTV Foil Infrared Decoys

Du J., Guan H., Li J.

Central European Journal of Energetic Materials

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2015

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Vol. 12, no. 4

855--863

EN

The aim of this project was to study how the particle size and morphology of magnesium powder affect the burning and infrared radiation characteristics of foil-type Mg/PTFE/Viton (MTV) infrared decoys. A long-wavelength thermal imager and an OPAG33 Fourier transform infrared remote-sensing spectrometer were used to characterize the burning and infrared radiation. The results show that the burning rate, burning temperature, and far-infrared radiation intensity of the decoys are improved significantly with decreased particle size. The burning rate, burning temperature, and far-infrared radiation intensity of the flake-like powder are higher than for the spherical powder of the same particle size.

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Synthesis, Spectral and Antiferromagnetic Interaction in Oxalato-Bridged Linear TRinuclear Oxovanadium(IV) Complexes

Li Y., Yan C., Guan H.

Polish Journal of Chemistry

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2004

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Vol. 78 / nr 2

187-194

EN

Three new linear trinuclear oxovanadium(IV) complexes bridged by oxalato (ox) and end-capped with 2,2_-bipyridine (bpy); 1,10-phenanthroline (phen) or 5-nitro-1,10- phenanthroline (NO2phen); respectively, namely [(VO)3(ox)2(bpy)2]SO4 (1), [(VO)3(ox)2(phen)2]SO4 (2) and [(VO)3(ox)2(NO2phen)2]SO4 (3), have been synthesized and characterized by elemental analyses, molar conductivity, magnetic measurements, IR, ESR and electronic spectral studies. It is proposed that these complexes have extended ox-bridged structures, consisting of three oxovanadium(IV) ions, each in a distorted square-pyramidal environment. Variable-temperature magnetic susceptibility measurements (4.2~300 K) of the complexes (1) and (2) revealed the occurrence of an intramolecular antiferromagnetic interaction between the oxovanadium(IV) ions through the oxalato-bridge within each molecule. The magnetic data have been also used to deduce the indicated structure. On the basis of spin Hamiltonian operator, _ _ _ H = 2J(S S S_ S_ ) 1 2 2 3 Ĺ + Ĺ , the magnetic analyses were carried out for the two trinuclear complexes and the spin-coupling constants (J) were evaluated as -9.85 cm-1 for (1) and -10.16 cm-1 for (2).

4

Synthesis of Ferromagnetic Cu3IICrIII-Type Heterotetranuclear Complexesv with Oxalato Bridges

Li Y., Yan C., Guan H.

Polish Journal of Chemistry

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2004

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Vol. 78 / nr 1

9-18

EN

Three new _-oxalato-bridgedCu3 IICrIII-type heterotetranuclear complexes have been synthesized and identified as: [Cu3Cr(ox)3(phen)3](ClO4)3 (1), [Cu3Cr(ox)3(Me2phen)3](ClO4)3 (2) and [Cu3Cr(ox)3(NO2phen)3](ClO4)3 (3), where ox represents the oxalato dianions; phen, Me2phen and NO2phen represent 1,10-phenanthroline; 2,9-dimethyl-1,10-phenanthroline or 5-nitro-1,10-phenanthroline respectively. These complexes are the first examples of [Cu3 IICrIII] species bridged by oxalato groups. The three complexes have not yet been isolated in crystalline form suitable for X-ray structure analysis, but based on elemental analyses, molar conductivity and magnetic moment (at room-temperature) measurements, IR, ESR and electronic spectral studies, these complexes are proposed to have oxalato-bridged structure consisting of three copper(II) ions and a chromium(III) ion, in which the chromium(III) ion has an octahedral environment, and the three copper(II) ions have a square-planar environment.Variable temperature magnetic susceptibility (4.2~300 K) measurements and studies of the complexes (1) and (2) revealed the occurrence of an intramolecular ferromagnetic interaction between the copper(II) and chromium(III) ions through the oxalato-bridge within each molecule. The magnetic data have been also used to deduce the indicated _-oxalato-bridged [Cu3 IICrIII] tetranuclear structure. On the basis of the spin Hamiltonian operator,_ _ _ _ _ _ _ H= 2J(S S S S S S Cu1 Cr Cu2 Cr Cu3 Cr Ĺ + Ĺ + Ĺ ), the magnetic analyses were carried out for the two CuII-CrIII heterotetranuclear complexes and the spin-coupling constants (J) were evaluated as +10.97 cm-1 for (1) and +9.28 cm-1 for (2), indicating that the bridging oxalato would be able to transmit ferromagnetic interaction in the strict orthogonality [Cu3 IICrIII] tetranuclear system.

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Synthesis and Magnetic Properties of Dinuclear Oxovanadium(IV) Complexes Bridged by Tetracarboxylato Groups

Li Y., Yan C., Guan H.

Polish Journal of Chemistry

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2004

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Vol. 78 / nr 1

1-7

EN

Three novel _-tetracarboxylato-bridged oxovanadium(IV) dinuclear complexes described by the overall formula [(VO)2(PMTA)L2], where PMTAstands for the tetraanion of pyromellitic acid, and L denotes 2,2_-bipyridine (bpy), 4,4_-dimethyl-2,2_-bipyridine (Me2bpy) or 1,10-phenanthroline (phen), respectively, have been synthesized and characterized by elemental analyses, molar conductivity and room-temperature magnetic moment measurements, IR, ESR and electronic spectral studies. It is proposed that these complexes have PMTA-bridged structures and consist of two oxovanadium(IV) ions, each in a square-pyramidal environment. The [(VO)2(PMTA)(bpy)2] (1) and [(VO)2(PMTA)(phen)2] (2) complexes were further characterized by variable temperature (4.2~300 K) magnetic susceptibility measurements and the observed data were fitted to the modified Bleaney-Bowers equation by the least-squares method, giving the exchange integral J = -2.75 cm-1 for (1) and J = -3.91 cm-1 for (2). This result indicates that there is a weak antiferromagnetic spin-exchange interaction between the two VO2+ ions within each molecule.