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Enhanced Non-linear Viscoelastic Properties of Polymer Bonded Explosives Based on Graphene and a Neutral Polymeric Bonding Agent

Lin C., He G., Liu J., Pan L., Liu S.

Central European Journal of Energetic Materials

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2017

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Vol. 14, no. 4

788--805

EN

During their long-term storage and transport, polymer bonded explosives (PBXs) will be subjected to complex thermal physical environments with combined thermal and mechanical loads. The creep behaviour results in a change of physical and mechanical properties, which consequently influences the explosive performance. In this work, graphene and a neutral polymeric bonding agent (NPBA) were selected to improve the non-linear creep properties of 1,3,5-triamino-2,4,6-trinitrobenzene (TATB)-based PBXs. The results were compared with the creep response of the corresponding PBXs without additives and with graphene alone. It was observed that graphene and an NPBA exhibited a positive effect, improving the creep resistance of TATB-based PBXs. The compressive and tensile strength of 0.5 wt.% graphene-filled PBXs were improved by 5.1% and 29.2%, respectively, compared to raw TATB-based PBXs without additives. The performance of the PBXs was further enhanced by the addition of 0.1 wt.% NPBA. For a given stress and temperature, the TATB-based PBXs with graphene and NPBA deformed significantly less than the PBXs filled with graphene alone.

2

Starch and nutrient contents are key for mosses adapting to different succession stages along a receding glacier

Sun S.-Q., He G., Wu Y.-H., Zhou J., Yu D.

Polish Journal of Ecology

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2013

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Vol. 61, nr 2

233--239

EN

Mosses are the pioneer and the first green land plants developed during the evolutionary process, they play an important role in the development of soil, biogeochemical cycling and facilitating plant colonization. Although species richness, composition, diversity and cover of moss communities vary, they grow well almost in all forests. Why mosses can grow in different conditions? What are the adaptive strategies of mosses in different forests along primary succession sequences? It is not still completely clear. In order to answer these questions, nutrient and carbohydrate accumulation in mosses were tested along the primary succession following deglaciation of Hailuogou glacier, Gongga Mountain, China. Nitrogen (N), phosphorus (P), potassium (K) content, total organic carbon (TOC), soluble sugar and starch accumulated in the dominant moss species were determined and compared. TOC increased insignificantly with forest age. N, P, K contents in mosses were significantly higher in forests with dense shrubs, where N content was seperately 1.69% in A. hookeri and 1.35% in P. schreberi in 30 yr aged forest, P content in 30 yr and 52 yr aged forest was seperately 0.022% and 0.020% in A. hookeri and 0.020% and 0.017% in P. schreberi, and K content in 30 yr and 52 yr aged forest was seperately 0.570% and 0.553% in A. hookeri and 0.490% and 0.493% in P. schreberi. Soluble sugar was higher in the early stage of succession, but the opposite was observed for starch and nonstructure carbohydrate content, which was lower in early successional stage. Mosses adopted different adaptive strategies in different aged forests along receding glacier, in which starch and N, P, K contents were key for adaptiation. That is, mosses accumulated much more starch in the severe environment of early succession stage. In more favourable environment, N, P, K was found to be accumulated for plant growth.

3

The application of the self-adaptive tracking method to the sinusoidal phase modulating interferometry

He G., Lu Y., Liao C., Zeng Z.

Optica Applicata

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2009

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Vol. 39, nr 1

109--122

EN

In this paper, we analyze theoretically the accuracy of the surface profile measurement in a sinusoidal phase modulating interferometer, derive the relative error formula, and investigate the influence of spectral leakage on the measurement accuracy. The theoretical results show that when the offset of sampling frequency from its theoretical ideal is outside the range of - 0.188% to +0.075%, the spectrum leakage results in an relative error greater than ?/320 nm, and thus the spectral leakage is not negligible. In order to eliminate the influence of the spectral leakage, a self-adaptive tracking method is proposed. The tracking method can adjust automatically the sampling signal frequency in such a way that the sampling signal frequency is an integer multiple of the modulating signal frequency. The simulation and experimental results show that the problem of the spectrum leakage can be solved with the proposed technique, and therefore the measurement accuracy and reliability of the SPM interferometer are enhanced.

4

Sinusoidal phase modulating interferometer for real-time surface profile measurement

He G., Jiang H., Tan X.

Optica Applicata

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2008

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Vol. 38, nr 2

413-420

EN

The optical interferometry for the surface profile measurement is high accuracy, non-contact, and has a wide application in industry and scientific research. In this paper, a sinusoidal phase modulating (SPM) interferometer to realize real-time surface profile measurement is proposed, and its measuring principle is analyzed theoretically. In the SPM interferometer, the interferencje signal is detected by a high speed image sensor based on a low-speed CCD and a signal processing circuit is used to obtain the phase of each point on the surface. Therefore, the surface profile can be measured real time. The experiments measuring the surface profile of a wedge-shaped optical flat show that the measurement time of the SPM interferometer is less than 10 ms, the repetitive measurement accuracy is 5.2 nm. The experimental results confirm the validity of the SPM interferometer, and the merits of the interferometer is simple structure, high measurement accuracy.