| 1. |
- Guo, Hao, et al.
(author)
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Heterogeneity and chemical reactivity of the remote troposphere defined by aircraft measurements
- 2021
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In: Atmospheric Chemistry And Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 21:18, s. 13729-13746
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Journal article (peer-reviewed)abstract
- The NASA Atmospheric Tomography (ATom) mission built a photochemical climatology of air parcels based on in situ measurements with the NASA DC-8 aircraft along objectively planned profiling transects through the middle of the Pacific and Atlantic oceans. In this paper we present and analyze a data set of 10 s (21(m) merged and gap-filled observations of the key reactive species driving the chemical budgets of O-3 and CH4 (O-3, CH4, CO, H2O, HCHO, H2O2, CH3OOH, C2H6, higher alkanes, alkenes, aromatics, NOx, HNO3, HNO4, peroxyacetyl nitrate, other organic nitrates), consisting of 146 494 distinct air parcels from ATom deployments 1 through 4. Six models calculated the O-3 and CH4 photochemical tendencies from this modeling data stream for ATom 1. We find that 80 %-90 % of the total reactivity lies in the top 50 % of the parcels and 25 %-35 % in the top 10 %, supporting previous model-only studies that tropospheric chemistry is driven by a fraction of all the air. In other words, accurate simulation of the least reactive 50 % of the troposphere is unimportant for global budgets. Surprisingly, the probability densities of species and reactivities averaged on a model scale (100 km) differ only slightly from the 2 km ATom data, indicating that much of the heterogeneity in tropospheric chemistry can be captured with current global chemistry models. Comparing the ATom reactivities over the tropical oceans with climatological statistics from six global chemistry models, we find excellent agreement with the loss of O-3 and CH4 but sharp disagreement with production of O-3. The models sharply underestimate O-3 production below 4 km in both Pacific and Atlantic basins, and this can be traced to lower NOx levels than observed. Attaching photochemical reactivities to measurements of chemical species allows for a richer, yet more constrained-towhat-matters, set of metrics for model evaluation.
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| 2. |
- Guo, Hao, et al.
(author)
-
Heterogeneity and chemical reactivity of the remote troposphere defined by aircraft measurements – corrected
- 2023
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In: Atmospheric Chemistry And Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 23:1, s. 99-117
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Journal article (peer-reviewed)abstract
- The NASA Atmospheric Tomography (ATom) mission built a photochemical climatology of air parcels based on in situ measurements with the NASA DC-8 aircraft along objectively planned profiling transects through the middle of the Pacific and Atlantic oceans. In this paper we present and analyze a data set of 10 s (2 km) merged and gap-filled observations of the key reactive species driving the chemical budgets of O3 and CH4 (O3, CH4, CO, H2O, HCHO, H2O2, CH3OOH, C2H6, higher alkanes, alkenes, aromatics, NOx, HNO3, HNO4, peroxyacetyl nitrate, and other organic nitrates), consisting of 146 494 distinct air parcels from ATom deployments 1 through 4. Six models calculated the O3 and CH4 photochemical tendencies from this modeling data stream for ATom 1. We find that 80 %–90 % of the total reactivity lies in the top 50 % of the parcels and 25 %–35 % in the top 10 %, supporting previous model-only studies that tropospheric chemistry is driven by a fraction of all the air. Surprisingly, the probability densities of species and reactivities averaged on a model scale (100 km) differ only slightly from the 2 km ATom 10 s data, indicating that much of the heterogeneity in tropospheric chemistry can be captured with current global chemistry models. Comparing the ATom reactivities over the tropical oceans with climatological statistics from six global chemistry models, we find generally good agreement with the reactivity rates for O3 and CH4. Models distinctly underestimate O3 production below 2 km relative to the mid-troposphere, and this can be traced to lower NOx levels than observed. Attaching photochemical reactivities to measurements of chemical species allows for a richer, yet more constrained-to-what-matters, set of metrics for model evaluation.
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| 3. |
- Nakamura, M., et al.
(author)
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Experimental verification of SDN/NFV in integrated mmwave access and mesh backhaul networks
- 2021
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In: IEICE transactions on communications. - : Institute of Electronics, Information and Communication, Engineers, IEICE. - 0916-8516 .- 1745-1345. ; E104B:3, s. 217-228
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Journal article (peer-reviewed)abstract
- In this paper, a Proof-of-Concept (PoC) architecture is constructed, and the effectiveness of mmWave overlay heterogeneous network (HetNet) with mesh backhaul utilizing route-multiplexing and Multi-access Edge Computing (MEC) utilizing prefetching algorithm is verified by measuring the throughput and the download time of real contents. The architecture can cope with the intensive mobile data traffic since data delivery utilizes multiple backhaul routes based on the mesh topology, i.e. route-multiplexing mechanism. On the other hand, MEC deploys the network edge contents requested in advance by nearby User Equipment (UE) based on pre-registered context information such as location, destination, demand application, etc. to the network edge, which is called prefetching algorithm. Therefore, mmWave access can be fully exploited even with capacity-limited backhaul networks by introducing the proposed algorithm. These technologies solve the problems in conventional mmWave HetNet to reduce mobile data traffic on backhaul networks to cloud networks. In addition, the proposed architecture is realized by introducing wireless Software Defined Network (SDN) and Network Function Virtualization (NFV). In our architecture, the network is dynamically controlled via wide-coverage microwave band links by which UE's context information is collected for optimizing the network resources and controlling network infrastructures to establish backhaul routes and MEC servers. In this paper, we develop the hardware equipment and middleware systems, and introduce these algorithms which are used as a driver of IEEE802.11ad and open source software. For 5G and beyond, the architecture integrated in mmWave backhaul, MEC and SDN/NFV will support some scenarios and use cases.
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| 4. |
- Nakamura, M., et al.
(author)
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Performance evaluation of prefetching algorithm for real-time edge content delivery in 5G system
- 2019
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In: IEEE Vehicular Technology Conference. - : IEEE. - 9781728112206
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Conference paper (peer-reviewed)abstract
- Recently, high-density deployment of mmWave small cell base stations has been focused as a means to cope with the rapidly increasing mobile data traffic. MmWave overlay heterogeneous network (HetNet) is proposed to realize eMBB, however laying cost of backbone utilizing high-capacity optical fibers is very costly to support ultra- broadband accesses. On the other hand, Multi- access Edge Computing (MEC) is proposed to reduce mobile data traffic on backhaul networks. MEC deploys contents requested by User Equipment (UE) nearby in advance based on registered context information e.g. location, destination, and required contents to the orchestrator. Therefore, it is possible to utilize mmWave access under existing backhaul networks by introducing prefetching algorithm. The architecture is enabled by wireless Software Defined Network (SDN) technology. In this paper, Proof-of-Concept (PoC) architecture is proposed, and the effectiveness of mmWave HetNet with MEC utilizing prefetching algorithm is confirmed by measuring the download time of real content.
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| 5. |
- Stålberg, Erik, et al.
(author)
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Electromyographic methods
- 2003
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In: Clinical Neurophysiology of Disorders of Muscle and Neuromuscular Junction, including Fatigue.. - : Elsevier B.V., Amsterdam. ; , s. 147-185
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Book chapter (peer-reviewed)
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| 6. |
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