| 1. |
- Chen, Jiajia, et al.
(author)
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Passive wide area network solutions : Filterless and semi-filterless optical networks
- 2011
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In: 13th International Conference on Transparent Optical Networks (ICTON). - 9781457708800
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Conference paper (peer-reviewed)abstract
- Advances in optical coherent transmission and electrical compensation technologies (such as coherent receiver and forward error correction FEC) have stimulated ideas for novel optical network architectures. Recently proposed passive wide area network solution, referred to as filterless optical network [1 #x2013;2] eliminates or minimizes the usage of active photonic reconfigurable network elements. In this approach, only the passive splitters and combiners for interconnecting the fiber links are utilized, which makes this network architecture more cost- and energy-effective as well as more reliable compared with networks based on active optical switching. However, the filterless optical network architecture implies some constraints on fiber interconnection design, maximum fiber-tree length and wavelength reuse due to its broadcast nature. Consequently, filterless solution always requires more resources (i.e. number of wavelengths) compared with the active switched optical networks which are allowed to utilize reconfigurable and coloured components. In order to improve the wavelength utilization while maintaining flexibility of resource allocation, this work extends the idea of filterless optical network by introducing some passive coloured components (e.g., fiber Bragg grating FBG, red/blue filters, etc) to drop local signals at some determined nodes. This approach is referred to as semi-filterless optical network. Furthermore, the semi-filterless solution maintains the passive feature, enabling high reliability and efficiency of cost and energy. Meanwhile, its non-broadcast property at some determined nodes has potential to decrease the transmission impairments and hence relax the constraints on fiber interconnection design and the maximal transparent length, which are strict in the filterless optical network. Our preliminary results confirm the advantages of semi-filterless solution.
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| 2. |
- Foley, Jonathan A., et al.
(author)
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Solutions for a cultivated planet
- 2011
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In: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 478:7369, s. 337-342
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Journal article (peer-reviewed)abstract
- Increasing population and consumption are placing unprecedented demands on agriculture and natural resources. Today, approximately a billion people are chronically malnourished while our agricultural systems are concurrently degrading land, water, biodiversity and climate on a global scale. To meet the world's future food security and sustainability needs, food production must grow substantially while, at the same time, agriculture's environmental footprint must shrink dramatically. Here we analyse solutions to this dilemma, showing that tremendous progress could be made by halting agricultural expansion, closing 'yield gaps' on underperforming lands, increasing cropping efficiency, shifting diets and reducing waste. Together, these strategies could double food production while greatly reducing the environmental impacts of agriculture.
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