| 1. |
- Ade, Peter, et al.
(författare)
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The Simons Observatory : science goals and forecasts
- 2019
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Ingår i: Journal of Cosmology and Astroparticle Physics. - : IOP Publishing. - 1475-7516. ; :2
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Tidskriftsartikel (refereegranskat)abstract
- The Simons Observatory (SO) is a new cosmic microwave background experiment being built on Cerro Toco in Chile, due to begin observations in the early 2020s. We describe the scientific goals of the experiment, motivate the design, and forecast its performance. SO will measure the temperature and polarization anisotropy of the cosmic microwave background in six frequency bands centered at: 27, 39, 93, 145, 225 and 280 GHz. The initial con figuration of SO will have three small-aperture 0.5-m telescopes and one large-aperture 6-m telescope, with a total of 60,000 cryogenic bolometers. Our key science goals are to characterize the primordial perturbations, measure the number of relativistic species and the mass of neutrinos, test for deviations from a cosmological constant, improve our understanding of galaxy evolution, and constrain the duration of reionization. The small aperture telescopes will target the largest angular scales observable from Chile, mapping approximate to 10% of the sky to a white noise level of 2 mu K-arcmin in combined 93 and 145 GHz bands, to measure the primordial tensor-to-scalar ratio, r, at a target level of sigma(r) = 0.003. The large aperture telescope will map approximate to 40% of the sky at arcminute angular resolution to an expected white noise level of 6 mu K-arcmin in combined 93 and 145 GHz bands, overlapping with the majority of the Large Synoptic Survey Telescope sky region and partially with the Dark Energy Spectroscopic Instrument. With up to an order of magnitude lower polarization noise than maps from the Planck satellite, the high-resolution sky maps will constrain cosmological parameters derived from the damping tail, gravitational lensing of the microwave background, the primordial bispectrum, and the thermal and kinematic Sunyaev-Zel'dovich effects, and will aid in delensing the large-angle polarization signal to measure the tensor-to-scalar ratio. The survey will also provide a legacy catalog of 16,000 galaxy clusters and more than 20,000 extragalactic sources.
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| 2. |
- Braun, Torsten, et al.
(författare)
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Power saving in wireless ad hoc networks without synchronization
- 2005. - 1
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Ingår i: 5th Scandinavian Workshop on Wireless Ad Hoc Networks (ADHOC'05).
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Konferensbidrag (refereegranskat)abstract
- Power saving strategies generally attempt to maximize the time that nodes spend in a low power consumption sleep state. Such strategies often require the sender to notify the receiver about pending traffic using some form of traffic announcement. Although asynchronous traffic announcement mechanisms are particularly suitable for the ad hoc environment, they also provide relatively limited power savings. This paper proposes a mechanism that improves the efficiency of asynchronous traffic announcement mechanisms by reducing the proportion of time that nodes need to spend awake, while still maintaining good connectivity properties. The mechanism is based on allowing traffic announcements to be rebroadcast by neighbouring nodes.
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| 4. |
- Dunkels, Adam, et al.
(författare)
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An integrated approach to developing sensor network solutions
- 2004. - 1
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Ingår i: Proceedings of the Second International Workshop on Sensor and Actor Network Protocols and Applications.
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Konferensbidrag (refereegranskat)abstract
- This paper describes a prototype sensor networking platform and its associated development environment. Key elements of the system are the ESB sensor hardware, the Contiki operating system, and the communication stack, which includes a MAC layer and a highly optimized TCP/IP. Because the work is driven by prototype applications being developed by project partners, particular attention is paid to the development environment and to practical deployment issues. Three prototype applications are also presented.
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| 6. |
- Feeney, Laura Marie, et al.
(författare)
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A geometric derivation of the probability of finding a relay in multi-rate networks
- 2004. - 1
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Konferensbidrag (refereegranskat)abstract
- Relaying can improve performance of a wireless network, especially when transmission modes with different distance/cost tradeoffs are available. Examples of such modes include data rates or transmission power. This paper geometrically analyzes the probability that a high-cost direct transmission can be replaced by a combination of low-cost relay transmissions. The main result of the analysis is a technology-agnostic characterization of a communication systems amenability to relaying strategies and some recommendations for how to structure such systems
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| 10. |
- Feeney, Laura Marie
(författare)
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A Taxonomy for Routing Protocols in Mobile Ad Hoc Networks
- 1999. - 1
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- A Mobile Ad hoc NETwork (manet) is a mobile, multi-hop wireless network which is capable of autonomous operation. It is characterized by energy-constrained nodes, bandwidth-constrained, variable-capacity wireless links and dynamic topology, leading to frequent and unpredictable connectivity changes. In the absence of a fixed infrastructure, manet nodes cooperate to provide routing services, relying on each other to forward packets to their destination. Routing protocols designed for the fixed network are not effective in the dynamic and resource-constrained manet environment; many alternative routing protocols have been suggested. This report provides an overview of a number of manet routing protocols. More importantly, it defines a taxonomy that is suitable for examining a wide variety of protocols in a structured way and exploring tradeoffs associated with various design choices. The emphasis is on practical design and implementation issues rather than complexity analysis.
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