| 1. |
- Luize, Bruno Garcia, et al.
(författare)
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Geography and ecology shape the phylogenetic composition of Amazonian tree communities
- 2024
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Ingår i: JOURNAL OF BIOGEOGRAPHY. - 0305-0270 .- 1365-2699.
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Tidskriftsartikel (refereegranskat)abstract
- Aim: Amazonia hosts more tree species from numerous evolutionary lineages, both young and ancient, than any other biogeographic region. Previous studies have shown that tree lineages colonized multiple edaphic environments and dispersed widely across Amazonia, leading to a hypothesis, which we test, that lineages should not be strongly associated with either geographic regions or edaphic forest types. Location: Amazonia. Taxon: Angiosperms (Magnoliids; Monocots; Eudicots). Methods: Data for the abundance of 5082 tree species in 1989 plots were combined with a mega-phylogeny. We applied evolutionary ordination to assess how phylogenetic composition varies across Amazonia. We used variation partitioning and Moran's eigenvector maps (MEM) to test and quantify the separate and joint contributions of spatial and environmental variables to explain the phylogenetic composition of plots. We tested the indicator value of lineages for geographic regions and edaphic forest types and mapped associations onto the phylogeny. Results: In the terra firme and v & aacute;rzea forest types, the phylogenetic composition varies by geographic region, but the igap & oacute; and white-sand forest types retain a unique evolutionary signature regardless of region. Overall, we find that soil chemistry, climate and topography explain 24% of the variation in phylogenetic composition, with 79% of that variation being spatially structured (R-2 = 19% overall for combined spatial/environmental effects). The phylogenetic composition also shows substantial spatial patterns not related to the environmental variables we quantified (R-2 = 28%). A greater number of lineages were significant indicators of geographic regions than forest types. Main Conclusion: Numerous tree lineages, including some ancient ones (>66 Ma), show strong associations with geographic regions and edaphic forest types of Amazonia. This shows that specialization in specific edaphic environments has played a long-standing role in the evolutionary assembly of Amazonian forests. Furthermore, many lineages, even those that have dispersed across Amazonia, dominate within a specific region, likely because of phylogenetically conserved niches for environmental conditions that are prevalent within regions.
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| 2. |
- Householder, John Ethan, et al.
(författare)
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One sixth of Amazonian tree diversity is dependent on river floodplains
- 2024
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Ingår i: NATURE ECOLOGY & EVOLUTION. - 2397-334X.
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Tidskriftsartikel (refereegranskat)abstract
- Amazonia's floodplain system is the largest and most biodiverse on Earth. Although forests are crucial to the ecological integrity of floodplains, our understanding of their species composition and how this may differ from surrounding forest types is still far too limited, particularly as changing inundation regimes begin to reshape floodplain tree communities and the critical ecosystem functions they underpin. Here we address this gap by taking a spatially explicit look at Amazonia-wide patterns of tree-species turnover and ecological specialization of the region's floodplain forests. We show that the majority of Amazonian tree species can inhabit floodplains, and about a sixth of Amazonian tree diversity is ecologically specialized on floodplains. The degree of specialization in floodplain communities is driven by regional flood patterns, with the most compositionally differentiated floodplain forests located centrally within the fluvial network and contingent on the most extraordinary flood magnitudes regionally. Our results provide a spatially explicit view of ecological specialization of floodplain forest communities and expose the need for whole-basin hydrological integrity to protect the Amazon's tree diversity and its function.
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| 3. |
- Arpanaei, F., et al.
(författare)
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Hyperaccelerated Power Optimization in Multi-Band Elastic Optical Networks
- 2024
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Ingår i: 2024 Optical Fiber Communications Conference and Exhibition, OFC 2024 - Proceedings.
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Konferensbidrag (refereegranskat)abstract
- We show that solving interrelated inverse differential equations can address pre-tilt power optimization, resulting in a few-second-computed optimal power for each span and boosting average channel generalized signal-to-the-noise ratio (GSNR) by up to 0.5 dB.
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| 4. |
- Ayoub, Omran, et al.
(författare)
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Towards Explainable Reinforcement Learning in Optical Networks: The RMSA Use Case
- 2024
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Ingår i: Conference on Optical Fiber Communication, Technical Digest Series.
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Konferensbidrag (refereegranskat)abstract
- We propose an approach to extract explanations from a trained reinforcement learning agent. Our analysis over three RMSA environment variations shows how the agent uses the input information, increasing our understanding of its learned policy.
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| 5. |
- Chen, Ling, et al.
(författare)
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Reliable and efficient RAR-based distributed model training in computing power network
- 2024
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Ingår i: Journal of Optical Communications and Networking. - 1943-0620 .- 1943-0639. ; 16:5, s. 527-540
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Tidskriftsartikel (refereegranskat)abstract
- The computing power network (CPN) is a novel network technology that integrates computing power from the cloud, edge, and terminals using IP/optical cross-layer networks for distributed computing. CPNs can provide an effective solution for distributed model training (DMT). As a bandwidth optimization architecture based on data parallelism, ring all-reduce (RAR) is widely used in DMT. However, any node or link failure on the ring can interrupt or block the requests deployed on the ring. Meanwhile, due to the resource competition of batch RAR-based DMT requests, inappropriate scheduling strategies will also lead to low training efficiency or congestion. As far as we know, there is currently no research that considers the survivability of rings in scheduling strategies for RAR-based DMT. To fill this gap, we propose a scheduling scheme for RAR-based DMT requests in CPNs to optimize the allocation of computing and wavelength resources considering the time dimension while ensuring reliability. In practical scenarios, service providers may focus on different performance metrics. We formulate an integer linear programming (ILP) model and a RAR-based DMT deployment algorithm (RDDA) to solve this problem considering four optimization objectives under the premise of the minimum blocking rate: minimum computing resource consumption, minimum wavelength resource consumption, minimum training time, and maximum reliability. Simulation results demonstrate that our model satisfies the reliability requirements while achieving corresponding optimal performance for DMT requests under four optimization objectives.
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| 6. |
- Etezadi, Ehsan, 1993, et al.
(författare)
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Programmable Filterless Optical Networks: Architecture, Design and Resource Allocation
- 2024
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Ingår i: IEEE/ACM Transactions on Networking. - 1558-2566 .- 1063-6692. ; 32:2, s. 1096-1109
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Tidskriftsartikel (refereegranskat)abstract
- Filterless optical networks (FONs) are a costeffective optical networking technology that replaces reconfigurable optical add-drop multiplexers, used in conventional, wavelength-switched optical networks (WSONs), by passive optical splitters and couplers. FONs follow the drop-and-waste transmission scheme, i.e., broadcast signals without filtering, which generates spectrum waste. Programmable filterless optical networks (PFONs) reduce this waste by equipping network nodes with programmable optical white box switches that support arbitrary interconnections of passive elements. Cost-efficient PFON solutions require optimal routing, modulation format and spectrum assignment (RMSA) to connection requests, as well as optimal design of the node architecture. This paper presents an optimization framework for PFONs. We formulate the RMSA problem in PFONs as a single-step integer linear program (ILP) that jointly minimizes the total spectrum and optical component usage. As RMSA is an NP-complete problem, we propose a two-step ILP formulation that addresses the RMSA sub-problems separately and seeks sub-optimal solutions to larger problem instances in acceptable time. Simulation results indicate a beneficial trade-off between component usage and spectrum consumption in proposed PFON solutions. They use up to 64% less spectrum than FONs, up to 84% fewer active switching elements than WSONs, and up to 81% fewer optical amplifiers at network nodes than FONs or WSONs.
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| 7. |
- Fernandes, Andre L.P., et al.
(författare)
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A Cost Assessment Methodology for User-Centric Distributed Massive MIMO Architectures
- 2024
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Ingår i: IEEE Open Journal of the Communications Society. - 2644-125X. ; In Press
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Tidskriftsartikel (refereegranskat)abstract
- User-centric (UC) distributed massive multiple-input multiple-output (D-mMIMO), also known as cell-free mMIMO, is a pivotal technology for enabling future mobile communication systems. While UC D-mMIMO intrinsically follows a distributed architecture, its processing can be implemented in a distributed or centralized fashion. This paper proposes a comprehensive cost assessment methodology for UC D-mMIMO, capturing its total cost of ownership and factoring in the deployment configuration, processing implementation, computational demands, and fronthaul signaling. The methodology considers two transmission reception point (TRP) deployment strategies. The first focuses only on supporting user equipment (UE) demands, while the other fulfills these requirements and also actively strives to provide a fairer service among UEs. The proposed methodology is then used to perform a techno-economic assessment of the feasibility of centralized versus distributed processing functional splits while varying key costs and TRP capabilities, like antenna and served UE count. Results suggest that with the TRP deployment that only supports the required UE rate, distributed processing is usually the most feasible option for UE demands of up to 50 Mbps, and centralized processing is more cost-effective in other cases. Additionally, when considering the actively fairer TRP deployment, centralized processing becomes cheaper for any UE demands.
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| 8. |
- Karunakaran, Vignesh, et al.
(författare)
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TAPI-based Telemetry Streaming in Multi-Domain Optical Transport Network
- 2024
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Ingår i: Optical Fiber Communications Conference and Exhibition (OFC) 2024. - 9781957171326
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Konferensbidrag (refereegranskat)abstract
- We demonstrate a TAPI-based telemetry streaming framework for automated service provisioning and monitoring in multi-domain optical networks. The demo showcases ML-based anomaly detection and network management across domains adhering to recommended YANG and protocol standards.
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| 9. |
- Natalino Da Silva, Carlos, 1987, et al.
(författare)
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AI/ML-as-a-Service for optical network automation: use cases and challenges [Invited]
- 2024
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Ingår i: Journal of Optical Communications and Networking. - 1943-0620 .- 1943-0639. ; 16:2, s. A169-A179
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Tidskriftsartikel (refereegranskat)abstract
- In recent years, artificial intelligence/machine learning (AI/ML) has played a significant role in automating opti- cal networks. Despite this, the methods for creating, deploying, and monitoring AI/ML models still rely heavily on human intervention and trial-and-error. AI/ML-as-a-Service aims at automating the processes associated with AI/ML models, reducing the need for human intervention and thus facilitating the widespread adoption of AI/ML models. In this paper, we introduce the concept of AI/ML-as-a-Service in the context of optical network automation and propose an architecture for realizing this concept. We provide details of a reference imple- mentation that focuses on the model creation stage. The reference implementation is tested using two use cases related to the quality-of-transmission (QoT) estimation of optical channels. We demonstrate that models created through AI/ML-as-a-Service are able to achieve similar performance as manually tuned models while drastically reducing the need for human involvement. Finally, we discuss future challenges and opportunities for applying AI/ML-as-a-Service in optical network automation.
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| 10. |
- Natalino Da Silva, Carlos, 1987, et al.
(författare)
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Analysis and Mitigation of Unwanted Biases in ML-based QoT Classification Tasks
- 2024
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Ingår i: Conference on Optical Fiber Communication, Technical Digest Series. - 9781957171326
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Konferensbidrag (refereegranskat)abstract
- We address the problem of mitigating biases in models used for the quality of transmission prediction. The proposed method reduces the relative accuracy difference between samples with different feature values by up to 45%.
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