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排序方式: 共有894条查询结果,搜索用时 31 毫秒
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844.
Clara Musa Roberta Licheri Antonio Mario Locci Roberto Orrù Giacomo Cao Miguel Angel Rodriguez Lucyna Jaworska 《Journal of Cleaner Production》2009,17(9):877-882
The conventional (hot pressing or HP) and the novel (spark plasma sintering or SPS) consolidation techniques were compared when processing Ti–Al2O3–TiC powders obtained by self-propagating high-temperature synthesis (SHS). It was found that the two different methods are able to produce similar materials, in some cases (Vickers hardness and wear rate) slightly better for SPSed samples. However, SPS does not need sintering temperatures as high as HP to obtain fully dense products. Most significantly, processing times were strongly reduced when adopting the SPS technique instead of HP, i.e. 4–7 min and about 5 h, respectively. Finally, when the total energies required during each SPS or HP experiment were compared, it was found that the use of the SPS technology allowed for an energy saving in the order of 90–95%. This fact makes SPS significantly advantageous from environmental and economical points of view compared to HP. 相似文献
845.
The present study was aimed at the reclamation of harbour sediments contaminated with butyltin compounds (BTCs) by means of biostimulation and/or bioaugmentation experiments carried out in a 5-L slurry bioreactor. In the biostimulation experiment with inorganic nutrients, almost 50% of TBT was degraded in 20 weeks. In the bioaugmentation experiment with a microbial consortium, no significant degradation of TBT was observed. Conversely, bioaugmentation combined with biostimulation led to a decrease of ~50% in TBT after four weeks. A simple kinetic model fitted to the experimental data of BTC concentration allowed us to estimate that 10 weeks are needed to decrease BTC contamination by 90% using a strategy based on both biostimulation and bioaugmentation, and 29 weeks for a strategy using biostimulation only. Overall, our study indicates that strategies based on biostimulation coupled to bioaugmentation can be effective in significantly reducing the concentration of BTCs over relatively short timescales. 相似文献
846.
Mario L. Ruz Francisco Vázquez Lorenzo Salas-Morera Antonio Cubero-Atienza 《Safety Science》2012,50(7):1606-1617
An experimental setup is proposed to test the performance of safety devices based on radio frequency technology. The setup specifically tests devices designed for improving safety in dangerous areas of small size, such as those surrounding power press brakes. Tested here is a radio frequency identification (RFID) prototype, whose main objective is to prevent accidents by sending a stop signal to a machine when a worker’s wrist, bearing an RFID tag, gets too close to the dangerous area. An ABB IRB 2400L robot is used as a reference system; this system is capable of providing millimeter accuracy. A plastic hand and a wristband with at least one passive RFID tag are attached to the end of the robot arm, which emulates the behavior of a human arm. With this robotic approach, it is possible to test trajectories with different velocities and orientations and to simulate several risky situations associated with machine use. Several experiments are presented that were conducted with the RFID prototype, and statistics are reported on the distance detection capability of this safety system with respect to the plane that defines the dangerous area. A matrix approach is proposed for analyzing the robustness of safety devices that are designed to automatically prevent a worker entering in dangerous areas. The results show the benefits that development of a radio frequency device of this class could confer towards increasing worker safety. 相似文献
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848.
Martina Milanese Antonio Sarà Gianluca Sarà Jason H. Murray 《Chemistry and Ecology》2013,29(2):95-105
This commentary describes a gap in the qualitative and quantitative knowledge of the provision of benefits to humans from the intertidal ecosystems of the Mediterranean and offers a framework for quantification of the benefits provided by these systems. The identification of such benefits, understanding their spatial distribution and their subsequent quantification will be critical to the design of policy responses to future climate change, sea level rise and seawater acidification. A baseline understanding of the current state of ecosystem functions, as well as of the provision of related ecosystem services, is therefore needed. Further, researchers must strive to generate forecasts of the changes in these functions and services conditional on policy responses and the range of expectations for climate change. 相似文献
849.
Marco Antonio Leonel Caetano Douglas Francisco Marcolino Gherardi Gustavo de Paula Ribeiro Takashi Yoneyama 《Ecological modelling》2009,220(19):2536-2542
The recent global financial crisis has highlighted the need for balanced and efficient investments in the reduction of the greenhouse effect caused by emissions of CO2 on a global scale. In a previous paper, the authors proposed a mathematical model describing the dynamic relation of CO2 emission with investment in reforestation and clean technology. An efficient allocation of resources to reduce the greenhouse effect has also been proposed. Here, this model is used to provide estimates of the investments needed in land reforestation and in the adoption of clean technologies for an optimum emission and abatement of CO2, for the period of 1996–2014. The required investments are computed to minimize deviations with respect to the emission targets proposed in the Kyoto Protocol for European Countries. The emission target can be achieved by 2014 with investments in reforestation peaking in 2004, and a reduction of the expected GDP of 42%, relative to 2006. Investments in clean technology should increase between 2008 and 2010 with maximum transfer figures around 70 million American dollars. Total (cumulative) costs are, however, relatively high depending on the price of carbon abatement and the rate at which the expected CO2 concentration in the atmosphere should be reduced. Results highlight the advantages for policy makers to be able to manage investments in climate policy more efficiently, controlling optimum transfers based on a portfolio of actions that tracks a pre-defined CO2 concentration target. 相似文献
850.
La Marca F Moroni M Cherubini L Lupo E Cenedese A 《Waste management (New York, N.Y.)》2012,32(7):1306-1315
The recovery of high-quality plastic materials is becoming an increasingly challenging issue for the recycling sector. Technologies for plastic recycling have to guarantee high-quality secondary raw material, complying with specific standards, for use in industrial applications. The variability in waste plastics does not always correspond to evident differences in physical characteristics, making traditional methodologies ineffective for plastic separation. The Multidune separator is a hydraulic channel allowing the sorting of solid particles on the basis of differential transport mechanisms by generating particular fluid dynamic conditions due to its geometric configuration and operational settings. In this paper, the fluid dynamic conditions were investigated by an image analysis technique, allowing the reconstruction of velocity fields generated inside the Multidune, considering two different geometric configurations of the device, Configuration A and Configuration B. Furthermore, tests on mono- and bi-material samples were completed with varying operational conditions under both configurations. In both series of experiments, the bi-material samples were composed of differing proportions (85% vs. 15%) to simulate real conditions in an industrial plant for the purifying of a useful fraction from a contaminating fraction. The separation results were evaluated in terms of grade and recovery of the useful fraction. 相似文献