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Author: Publisher: ISBN: Category : Aeronautics Languages : en Pages : 1282
Book Description
Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.
Author: Publisher: ISBN: Category : Aeronautics Languages : en Pages : 1282
Book Description
Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.
Author: Alec Lumsden Publisher: Crowood Press (UK) ISBN: Category : History Languages : en Pages : 342
Book Description
This is a record of more than 250 basic types of British aero engine built between 1909 and 1949. In some 900 variants, they powered 300 different types of aircraft both civil and military. This volume gives a cross-reference of all aircraft engine types, variants and the aircraft they powered.
Author: Hien Quoc Ngo Publisher: Linköping University Electronic Press ISBN: 9175191474 Category : Languages : en Pages : 69
Book Description
The last ten years have seen a massive growth in the number of connected wireless devices. Billions of devices are connected and managed by wireless networks. At the same time, each device needs a high throughput to support applications such as voice, real-time video, movies, and games. Demands for wireless throughput and the number of wireless devices will always increase. In addition, there is a growing concern about energy consumption of wireless communication systems. Thus, future wireless systems have to satisfy three main requirements: i) having a high throughput; ii) simultaneously serving many users; and iii) having less energy consumption. Massive multiple-input multiple-output (MIMO) technology, where a base station (BS) equipped with very large number of antennas (collocated or distributed) serves many users in the same time-frequency resource, can meet the above requirements, and hence, it is a promising candidate technology for next generations of wireless systems. With massive antenna arrays at the BS, for most propagation environments, the channels become favorable, i.e., the channel vectors between the users and the BS are (nearly) pairwisely orthogonal, and hence, linear processing is nearly optimal. A huge throughput and energy efficiency can be achieved due to the multiplexing gain and the array gain. In particular, with a simple power control scheme, Massive MIMO can offer uniformly good service for all users. In this dissertation, we focus on the performance of Massive MIMO. The dissertation consists of two main parts: fundamentals and system designs of Massive MIMO. In the first part, we focus on fundamental limits of the system performance under practical constraints such as low complexity processing, limited length of each coherence interval, intercell interference, and finite-dimensional channels. We first study the potential for power savings of the Massive MIMO uplink with maximum-ratio combining (MRC), zero-forcing, and minimum mean-square error receivers, under perfect and imperfect channels. The energy and spectral efficiency tradeoff is investigated. Secondly, we consider a physical channel model where the angular domain is divided into a finite number of distinct directions. A lower bound on the capacity is derived, and the effect of pilot contamination in this finite-dimensional channel model is analyzed. Finally, some aspects of favorable propagation in Massive MIMO under Rayleigh fading and line-of-sight (LoS) channels are investigated. We show that both Rayleigh fading and LoS environments offer favorable propagation. In the second part, based on the fundamental analysis in the first part, we propose some system designs for Massive MIMO. The acquisition of channel state information (CSI) is very importantin Massive MIMO. Typically, the channels are estimated at the BS through uplink training. Owing to the limited length of the coherence interval, the system performance is limited by pilot contamination. To reduce the pilot contamination effect, we propose an eigenvalue-decomposition-based scheme to estimate the channel directly from the received data. The proposed scheme results in better performance compared with the conventional training schemes due to the reduced pilot contamination. Another important issue of CSI acquisition in Massive MIMO is how to acquire CSI at the users. To address this issue, we propose two channel estimation schemes at the users: i) a downlink "beamforming training" scheme, and ii) a method for blind estimation of the effective downlink channel gains. In both schemes, the channel estimation overhead is independent of the number of BS antennas. We also derive the optimal pilot and data powers as well as the training duration allocation to maximize the sum spectral efficiency of the Massive MIMO uplink with MRC receivers, for a given total energy budget spent in a coherence interval. Finally, applications of Massive MIMO in relay channels are proposed and analyzed. Specifically, we consider multipair relaying systems where many sources simultaneously communicate with many destinations in the same time-frequency resource with the help of a massive MIMO relay. A massive MIMO relay is equipped with many collocated or distributed antennas. We consider different duplexing modes (full-duplex and half-duplex) and different relaying protocols (amplify-and-forward, decode-and-forward, two-way relaying, and one-way relaying) at the relay. The potential benefits of massive MIMO technology in these relaying systems are explored in terms of spectral efficiency and power efficiency.
Author: Mark Warner Publisher: Penguin ISBN: 1101142367 Category : Transportation Languages : en Pages : 480
Book Description
Transform an average car or truck into a turbocharged high performance street machine. A handbook on theory and application of turbocharging for street and high-performance use, this book covers high performance cars and trucks. This comprehensive guide features sections on theory, indepth coverage of turbocharging components, fabricating systems, engine building and testing, aftermarket options and project vehicles.
Author: Bill Gunston Publisher: Haynes Publishing ISBN: Category : Reference Languages : en Pages : 216
Book Description
A reference work describing every major aeroplane engine manufacturer throughout the world, together with its products, from the pioneering days to the recent engines. Each aero engine is within its technological and historical context with power plants of all nationalities illlustrated. The human element of the story is also included with the personal struggles that resulted in such notable engines as the Rolls-Royce Merlin and the Pratt & Whitney P6 being related.
Author: Daniel Sharp Publisher: ISBN: 9781910809020 Category : Space shuttles Languages : en Pages : 0
Book Description
Even as America and Russia stepped up their efforts in the early 1960s to design ever faster bombers and put men and equipment into space, Britain quietly set to work devising its own hypersonic aircraft and manned space vehicles. British Secret Projects 5: Britain's Space Shuttletells the story of how, from 1963 to 1966, English Electric/BAC's Preston works secretly led the world in re-useable spacecraft design. A huge variety of designs formed the P.42 project with more than 100 proposals for hypersonic interceptors, bombers, reconnaissance aircraft, satellite launchers, spacecraft launchers, orbital spy planes and satellite killers. The end result was the 'Multi-Unit Space Transport And Recovery Device' (MUSTARD), which pre-dated the USA's Space Shuttle program by six years. Based on unique access to the original project drawings, photographs, archives and interviews with surviving members of the design team, British Secret Projects 5: Britain's Space Shuttleoffers a unique insight into this hitherto little-known chapter in the secret history of the UK manned space flight program.
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Author: Alec Lumsden
Author: Dorothy Levitt
Author: J. Paulo Davim
Author: Hien Quoc Ngo
Author: Mark Warner
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Author: Bill Gunston
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Author: Daniel Sharp