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1.
Daniel Kohl C. von Boyneburgk M. Feldmann H.-P. Heim S. Böhm 《Wood material science & engineering》2020,15(3):130-139
ABSTRACTDue to its naturally grown properties, wood has played a rather subordinate role as a material for technical applications up to now. In this paper, multi-material systems based on veneers of beech (Fagus sylvatica) with different reinforcing variants were investigated. In addition to the influence of different adhesive systems (urea formaldehyde and polyurethane), the effect of reinforcing by aramid fiber fabric and stainless steel foil in different climates was examined. At the center of the investigations were dynamically sudden loads, in the form of impact bending and dart drop tests (penetration and impact mode). It has been shown that the use of the reinforcing materials leads to a significant improvement in material properties. The penetration energy of the composites reinforced with the aramid fiber fabric could be increased by 43%. The maximum force in the dart drop test (impact mode) could be increased by 29% with the stainless steel foil, the damping decreased by 48%. The aramid fiber reinforcement achieved an increase in impact resistance by 27% in impact bending test, the steel reinforced achieved an increase of 39%. A clear dependency on both, the climate and the adhesive within the composite, could be demonstrated. 相似文献
2.
Sabine Augustin Jan Evers Hans-Peter Dietrich Johannes Eichhorn Thomas Haussmann Regina Icke Ansgar Isenberg Wolfgang Lux Monica Musio Hans Pretzsch Winfried Riek Thomas Rötzer Bernd Schultze Andreas Schulze Jörg Schröder Walter Seidling Nicole Wellbrock Klaus von Wilpert Barbara Wolff 《European Journal of Forest Research》2005,124(4):251-260
In the 1970s unexpected forest damages, called “new type of forest damage” or “forest decline”, were observed in Germany and
other European countries. The Federal Republic of Germany and the German Federal States implemented a forest monitoring system
in the early 1980s, in order to monitor and assess the forest condition. Due to the growing public awareness of possible adverse
effects of air pollution on forests, in 1985 the ICP Forests was launched under the convention on long-range transboundary
air pollution (CLRTAP) of the United Nations Economic Commission for Europe (UN-ECE). The German experience in forest monitoring
was a base for the implementation of the European monitoring system. In 2001 the interdisciplinary case study “concept and
feasibility study for the integrated evaluation of environmental monitoring data in forests”, funded by the German Federal
Ministry of Education and Research, concentrated on in-depths evaluations of the German data of forest monitoring. The objectives
of the study were: (a) a reliable assessment of the vitality and functioning of forest ecosystems, (b) the identification
and quantification of factors influencing forest vitality, and (c) the clarification of cause-effect-relationships leading
to leaf/needle loss. For these purposes additional data from external sources were acquired: climate and deposition, for selected
level I plots tree growth data, as well as data on groundwater quality. The results show that in particular time series analysis
(crown condition, tree growth, and tree ring analysis), in combination with climate and deposition are valuable and informative,
as well as integrated evaluation of soil, tree nutrition and crown condition data. Methods to combine information from the
extensive and the intensive monitoring, and to transfer process information to the large scale should be elaborated in future.
相似文献
Sabine AugustinEmail: |
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丹江口水源涵养区绿色高效农业技术创新集成与示范——模式设计、技术集成与机制创新 总被引:3,自引:3,他引:0
2017年5月,中国农业科学院科技创新工程协同创新任务“丹江口水源涵养区绿色高效农业技术创新集成与示范”正式启动。项目在农业绿色高效生产、种养耦合、生态循环、面源污染控制、多功能田园生态系统构建等方面开展协同创新。按照单一技术规范化、复合技术集成化、体系技术系统化的思路,任务创新集成水源涵养区生物多样性利用与农业种植结构调整、主要农产品全产业链绿色高效生产、种养循环新模式、生态型高效设施农业、农村生活污染物控制等环节的十大关键技术,总结形成一套水源涵养区绿色高效农业全域综合性的技术解决方案,可为其他同类地区提供可复制、可推广的经验、模式和示范样板,为保障南水北调水质安全,推动水源涵养区农业绿色发展、农民增收及区域脱贫攻坚提供有效的科技支撑。 相似文献
5.
农业面源污染负荷空间分布及风险评价研究进展 总被引:2,自引:1,他引:1
为了研究农业面源污染负荷空间分布及风险评估,综述了国内外近10年的最新研究进展,发现在农业面源污染空间分布及风险评估上的研究较多,其中污染的源因子及迁移因子空间分布研究进展颇多,而在综合风险评价上的研究还比较缺乏,对污染负荷的分布特征及其相关性的研究还存在不足,今后还需研究污染负荷分级区划与管理控制措施研究。 相似文献
6.
温度在气体污染物扩散的过程中起一定的作用。在现实生活中,由于日晒和地表辐射的存在,使得地面、建筑物外表面都与空气存在一定的温差。温差的存在会改变地表及壁面附近的流场,从而对住宅区污染物的扩散产生影响。利用理论推导对热力因素及扩散因素的关系进行了研究,并且与数值模拟的试验结果进行比较。结果发现理论推导与试验结果整体趋势相一致。这表明在与无温差情况相比较,温差存在时,地表及壁面附近流场更加紊乱;温差与气体污染物的扩散具有正相关性,对住宅区污染物的稀释起积极作用。 相似文献
7.
Loss reduction is important for distribution networks and it is available to reduce loss by loads equalization. With increasing numbers of vertexes in distribution networks, compounding of loads are rapid increasing. It is hard to achieve the global optimization for load balancing by traditional model of distribution networks. Base on analyzing character of loads equalization for distribution networks, this paper provides a new method which conjugate the optimization principle and the hierarchical model of the distribution networks, can transfer the optimization issues into multi stage decision making problems,and can also achieve the optimization equalization of the distribution networks loads. 相似文献
8.
You lihua Wu Huibi Sun Renbo Wang Daivu 《保鲜与加工》1992,(4):48-53
The basic equations of wall plates of MAN' S dry gas holders are derived in this paper. According to the law of cylindrical bending given by the finite element results .we derive some approximate formula calculating the deflection and stresses of the wall plates from the basic equations. Compared with the known approximate calculating method.the method car. obviously increase the percision. 相似文献
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多源沉积物对地表水中磷铜锌浓度的影响 总被引:1,自引:1,他引:1
受多来源沉积物污染影响的水体中可溶性P,Cu,Zn实际浓度常明显低于按各自沉积物的比例与释放量计算的理论值。沉积物之间的性质差异越大,实际测定值与计算值之间的差异也越大。多来源沉积物水体中可溶性P,Cu,Zn的浓度主要受P,Cu,Zn释放能力最强或对P,Cu,Zn吸持能力最强的沉积物比例控制。 相似文献