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101.
102.
Michaela Poppe Kerstin Böck Andreas Zitek Sigrid Scheikl Andreas Loach Susanne Muhar 《?sterreichische Wasser- und Abfallwirtschaft》2016,68(7-8):342-353
River landscape planning and management to promote the positive long-term development of river landscapes must adhere to the principle of sustainability. In this context, the goal is to initiate a development process for river landscapes that successfully reconciles the requirements of nature and water conservation with social and economic aspects, and which actively involves affected citizens in the decision-making process. A systems-based understanding and the opportunity to make ecologically relevant decisions are essential prerequisites for participative processes. 相似文献
103.
In this paper, we propose a tabu search algorithm for the resource-constrained project scheduling problem with transfer times. Solutions are represented by resource flows extending the disjunctive graph model for shop scheduling problems. Neighborhoods are defined by parallel and serial modifications rerouting or reversing flow on certain arcs. This approach is evaluated from a theoretical and experimental point of view. Besides studying the connectivity of different neighborhoods, computational results are presented for benchmark instances with and without transfer times. 相似文献
104.
Time‐resolved small‐angle X‐ray scattering study of void fraction evolution in high‐density polyethylene during stress unloading and strain recovery 下载免费PDF全文
Frédéric Addiego Stanislav Patlazhan Kui Wang Stéphane André Sigrid Bernstorff David Ruch 《Polymer International》2015,64(11):1513-1521
By means of time‐resolved small‐angle X‐ray scattering, we developed an analysis methodology to assess the void volume fraction ?v in high‐density polyethylene (HDPE) during tensile testing. The specimens were first drawn up to different imposed strains, and subsequently were subjected to stress unloading and strain recovery stages. During the loading stage, ?v progressively increased with the strain level, starting from a well‐defined onset strain prior to the yield point. In particular, ?v reached a maximum of 8.75 vol% for a strain of 12.5% in the case of a HDPE grade with a molecular weight of 105 000 g mol?1. Stress unloading and strain recovery caused a decrease in ?v attained at the end of the loading stage. For a HDPE grade with a molecular weight of 55 000 g mol?1, ?v was more important during the loading stage and the decrease in ?v was less marked during the stress unloading stage when compared to the HDPE with molecular weight of 105 000 g mol?1. The residual and reversible components of void volume fraction were revealed. © 2015 Society of Chemical Industry 相似文献
105.
Graham Kendall Sigrid Knust Celso C. Ribeiro Sebastián Urrutia 《Computers & Operations Research》2010,37(1):1-19
Sports have worldwide appeal. Professional sport leagues involve significant investments in players. Events such as the Olympics Games, the Football World Cup and the major golf and tennis tournaments generate huge worldwide television audiences and many sports are multi-million dollar industries. A key aspect of sporting events is the ability to generate schedules that optimize logistic issues and that are seen as fair to all those who have an interest. This is not just restricted to generating the fixtures, but also to other areas such as assigning officials to the games in the competitions. This paper provides an annotated bibliography for sports scheduling articles. This area can be traced back over 40 years. It is noticeable that the number of papers has risen in recent years, demonstrating that scientific interest is increasing in this area. 相似文献
106.
Øyvind Borg Edd A. Blekkan Sigrid Eri Duncan Akporiaye Bente Vigerust Erling Rytter Anders Holmen 《Topics in Catalysis》2007,45(1-4):39-43
The effect of calcination temperature and atmosphere on the properties of γ-Al2O3 supported cobalt Fischer-Tropsch catalysts has been investigated. One common precursor for all the catalysts was prepared
by incipient wetness impregnation of γ-Al2O3 with an aqueous solution of cobalt nitrate hexahydrate. It was subjected to four different calcination atmospheres (air/50%
steam: 30 mL/min, air: 30 mL/min, air: 50 mL/min, N2: 30 mL/min) and eight different calcination temperatures (range: 473–723 K), making the total number of samples 32. Both
the post calcination nitrogen content and the cobalt dispersion were measured. The results demonstrated that in order to maximise
the cobalt dispersion, it is necessary to use low calcination temperatures and remove the precursor decomposition products
(NO, NO2, H2O) efficiently. The Fischer-Tropsch synthesis performance of two catalysts calcined at the same temperature, but at different
air flow rates was evaluated. No significant effect of the air flow rate was found on the turnover frequency or C5+ selectivity, but a high flow rate resulted in 30% higher activity per gram catalyst. 相似文献
107.
108.
Tine Tysmans Sigrid Adriaenssens Heidi Cuypers Jan Wastiels 《Composites Science and Technology》2009,69(11-12):1790-1796
The reinforcement of cement with glass fibre textiles imbues the composite with a tensile as well as compressive load-bearing capacity. The tensile capacity allows the elimination of steel reinforcement as well as the concrete corrosion cover in structural applications. With textile reinforced concrete (TRC) thin and/or free form shells could be realized. In this paper, a parametric study is used to evaluate the structural applicability of TRC for small span (2–15 m) doubly curved roof shells. The application of two different, existing TRC material combinations demonstrates the influence of the applied composite material on the design of the shell. 相似文献
109.
The present study worked out the effects of the additive package on both the degradation behavior and the thermal properties of a commercial polyoxymethylene (POM) homopolymer (Delrin® 900P) during an artificial thermooxidative aging. The POM pellets were investigated as received and after a storage duration of 5 weeks at 140°C in an oven. Additionally, the pellets for the initial and aged conditions were purified to remove the additives. The degradation behavior was determined by means of thermogravimetric analysis (TGA), while the thermal properties were studied with differential scanning calorimetry (DSC). Further, optical microscopy and Fourier transform infrared spectroscopy were used to follow changes occurring during the artificial aging. Dynamic TGA in nitrogen and air showed that even after a severe aging procedure, some thermooxidative stabilizer was still present. However, its effectiveness was no longer good, as the aged POM showed a lower degradation temperature than the initial material. This result is evidence that thermally sensitive and more volatile compounds were formed. Purification of the aged pellets led to a material that degraded immediately during melting. Isothermal DSC experiments carried out at several temperatures showed that the elimination of the additives increased the crystallization rate. The crystallization kinetics could be described by using the Avrami model. J. VINYL ADDIT. TECHNOL, 2008. © 2008 Society of Plastics Engineers 相似文献
110.
Colin Crews Dominic Roberts Sigrid Lauryssen Gerard Kramer 《Food Additives and Contaminants: Part B: Surveillance Communications》2013,6(2):95-98
Canned and jarred baby foods (74), canned and jarred adult foods (63) and 70 coffees sold in Belgium, Italy, Portugal, Spain and The Netherlands were analysed for their furan content using a validated automated headspace GC–MS procedure. Seven balsamic vinegars from Italy and Spain were also analysed. All 74 baby food samples contained detectable furan, with an average level of 37 ng/g. A total of 54 of 63 canned and jarred foods contained detectable furan with an average level of 24 ng/g. Levels of furan in coffee as consumed were very variable and reflected different preparation methods and coffee strengths. Over 50% of Italian samples contained more than 200 ng/g, whereas over 20% of Belgian coffees contained less than 21 ng/g furan. Some brews made from fine grained coffee contained much more furan than did brews made from normal or coarse grained coffee. Although furan was low in most instant coffees, two Italian products “instant espresso” and “instant mocha” contained about 150 ng/g furan. Balsamic vinegars from Spain contained 159–662 ng/g of furan; however, other samples from Spain and Italy contained only 6–25 ng/g. 相似文献