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毛纺科技 2019年第12期47卷 1-5页

作者：刘晓东 muluneh bekele haile 李瑞霞常军李延刚吴大诚成都纺织高等专科学校纤维材料创新中心四川成都611731 巴哈达大学埃塞俄比亚国立纺织与服装技术研究所巴哈达四川大学纺织研究所四川成都610065

采用传统环锭纺工艺,将聚醚酯(PEE)和聚对苯二甲酸丁二酯(PBT)共混体弹性短纤维纺制成弹性纱,研究弹性纤维纺纱工艺的原理和参数的选择,分析弹性短纤维和弹性纱的应力-应变行为及其弹性回复性,按照高柳素夫的方式给出了PEE-PBT共混体弹... 详细信息

采用传统环锭纺工艺,将聚醚酯(PEE)和聚对苯二甲酸丁二酯(PBT)共混体弹性短纤维纺制成弹性纱,研究弹性纤维纺纱工艺的原理和参数的选择,分析弹性短纤维和弹性纱的应力-应变行为及其弹性回复性,按照高柳素夫的方式给出了PEE-PBT共混体弹性的力学模型,可以解释制得纤维和纱线的高弹性。实验表明:由该聚醚酯共混体短纤维制造的弹性纱,在定伸长15%时,弹性回复率仍大于95%;而对该弹性纱循环拉伸后的弹性回复测试表明:在6次循环拉伸20%后的弹性回复率仍达到了90%,采用弹性短纤维可以成功纺制弹性纱。

关键词：聚醚酯共混体弹性纤维环锭纺弹性纱弹性回复高弹性

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维普期刊数据库

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Plant community and ecological analysis of woodland vegetation in Metema Area,Amhara National Regional State,Northwestern Ethiopia

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Journal of Forestry Research 2012年第4期23卷 599-607页

作者： haile Adamu Wale Tamrat bekele Gemedo Dalle Ethiopian Institute of Agricultural Research Debre Zeit Agricultural Research CenterP.O.Box 32Debre ZeitEthiopia Addis Ababa University Faculty of Life SciencesP.O.Box 1176Addis AbabaEthiopia Institute of Biodiversity Conservation P.O.Box 80119Addis AbabaEthiopia

We studied woodland vegetation in broad-leaved deciduous woodlands of Metema in northwestern Amhara regional state, Ethiopia to determine plant community types and species distribution patterns and their relationships with environmental variables, including altitude, pH, cation exchange capacity, electrical conductivity （EC）, and moisture. We used a selective approach with a systematic sampling design. A total of 74 quadrats, each 25m × 25m at intervals of 150-200 m were sampled along the established transect lines. For herbaceous vegetation and soil data collection, five subquadrats each lm x lm were established at the four corners and the center of each quadrat. Three community types were identified using TWINSPAN analysis. All three community types showed high diversity （Shannon-Weiner index）, the highest in community type II at 3.55. The highest similarity coefficient was 0.49 （49%） between community types II and III, reflecting 0.51 （51%） dissimilarity in their species richness. The canonical correspondence ordination diagram revealed that the distribution pattern of community type I was explained by moisture while that of community types III and II was explained by EC and altitude and moisture, respectively. Altitude was the most statistically significant environmental variable, followed by moisture and EC in determining the total variation in species composition and distribution patterns while pH and cation exchange capacity were non significant. In conclusion, we recommend that any intervention should take into account these three discrete community types and their environmental settings to make the intervention more successful.

关键词： equitability diversity dryland environmental variables ordination metema woodland plant community types similarity

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维普期刊数据库

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Floristic diversity, regeneration status, and vegetation structure of woodlands in Metema Area, Amhara National Regional State, North-western Ethiopia

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Journal of Forestry Research 2012年第3期23卷 391-398页

作者： haile Adamu Wale Tamrat bekele Gemedo Dalle Ethiopian Institute of Agricultural Research Debre Zeit Agricultural Research CenterP.O.Box 32Debre ZeitEthiopia Addis Ababa University Faculty of Life SciencesP.O.Box 1176AddisAbabaEthiopia Institute of Biodiversity Conservation P.O.Box 80119Addis AbabaEthiopia

We studied woodland vegetation in broad-leaved deciduous woodlands of Metema in northwestern Amhara regional state, Ethiopia Our objective was to describe plant species composition, diversity, re- generation status, and population structure by a selective approach with a systematic sampling design. A total of 74 quadrats （each for 25 m x 25 m, spaced at intervals of 150--200 m） were sampled along established tran- sect lines following the homogeneity of the vegetation. Vegetation data including cover-abundance, height, diameter at breast height （DBH）, and numbers of seedlings and saplings of woody species were analyzed using Excel spreadsheet, Shannon Weiner diversity index, and PAST version 1.62. A total of 87 vascular plant species of 74 genera and 36 families were recorded. The dominant family was Fabaceae represented by 16 （18.39 %） species of 13 genera. Shannon Weiner diversity and evenness were 3.67 and 0.82, respectively, which showed that the area was en- dowed with rich floral diversity evenly distributed. The vegetation structure, as quantified by cumulative diameter class frequency distribution, plotted as an interrupted inverted-J- shape pattern with a sharp decrease in the 2nd diameter class. This indicated poor vegetation structure. The diameter classes frequency distributions of selected species plotted in four general patterns i.e., interrupted Inverted-J-shape, J-shape, Bell-shape and Irregular-shape. In conclusion, although the area showed high floral diversity and evenness, woody species including Sterculea setigera, Boswellia papyrifera, and Pterocarpus lucens showed lowest recruitment of seedlings and saplings.

关键词： equitability diversity dryland Metema Woodland popula- tion structure regeneration

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维普期刊数据库

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