Nasa launches a free public library of 140,000 iconic images and recordings from space

140,000 iconic images and recordings from space

In the 59 years since it was first founded, Nasa has taken some of the most iconic videos and images of space.

Now, in a bid to make this media as accessible as possible, the space agency has launched its new image and video Library.

Members of the public can now search and download more than 140,000 images, videos and audio files, including stunning views of Mars, and the famous first steps on the moon in 1969.

https://images.nasa.gov

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Advanced Design Techniques for RF Power Amplifiers

Whether you are a researcher, or practising engineer, or even non-familiar with power amplifiers student, it is a good idea to look into Advanced Design Techniques for RF Power Amplifiers . Its main aim is to provide the reader with a deep analysis of theoretical aspects, modelling, and design strategies of RF high-efficiency power amplifiers. Advanced Design Techniques for RF Power Amplifiers begins with an analytical review of current state of the problem. Then it moves to the theoretical analysis of BJT class-F power amplifier near transition frequency and presents the necessary realization conditions. The next part concerns the practical verification and demonstration of the theoretical results. It is followed by the part devoted to the output networks of high-efficiency power ampifiers. The novel type of photonic band-gap structure providing improved characteristics both in the pass and stop bands is proposed. Finally, the fifth-harmonic peaking class F power amplifier design based on the above structure is presented. Advanced Design Techniques for RF Power Amplifiers can be used as a guide by scientists and engineers dealing with this subject and as a text book to graduate and postgraduate students. The latter will find the comprehensive nonlinear power amplifiers simulation tutorial in the Appendix. It provides an excellent quick start for beginners, although the main contents is intended for a skilled reader.

Advanced Design Techniques for RF Power Amplifiers

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Calibration Techniques in Nyquist A/D Converters

In modern systems signal processing is performed in the digital domain. Contrary to analog circuits, digital signal processing offers more robustness, programmability, error correction and storage possibility. The trend to shift the A/D converter towards the input of the system requires A/D converters with more dynamic range and higher sampling speeds. This puts extreme demands on the A/D converter and potentially increases the power consumption. Calibration Techniques in Nyquist A/D Converters analyses different A/D-converter architectures with an emphasis on the maximum achievable power efficiency. It is shown that in order to achieve high speed and high accuracy at high power efficiency, calibration is required. Calibration reduces the overall power consumption by using the available digital processing capability to relax the demands on critical power hungry analog components. Several calibration techniques are analyzed. The calibration techniques presented in this book are applicable to other analog-to-digital systems, such as those applied in integrated receivers. Further refinements will allow using analog components with less accuracy, which will then be compensated by digital signal processing. The presented methods allow implementing this without introducing a speed or power penalty.

Calibration Techniques in Nyquist A/D Converters

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Mobile Ad Hoc Networks

This book presents the Time Reservation using Adaptive Control for Energy Efficiency (TRACE) family of protocol architectures that provide such dynamic coordinated channel access in a distributed manner, enabling energy-efficient, real-time data communications in MANETs. Furthermore, this book provides an introduction to the fundamentals of MANETs, an overview of protocols for each layer of the protocol stack, and a discussion of the issues involved with energy-efficient protocol design and quality of service for real-time data transmission.

Mobile Ad Hoc Networks

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The Fernow Watershed Acidification Study

In the late 1980’s, a considerable amount of research addressing the effects of acidic deposition was begun, much of it related to the Congr- sionally mandated National Atmospheric Precipitation Assessment Program (NAPAP). As a result of the 10-year NAPAP program, effects on human health, materials, structures, visibility and terrestrial and aquatic ecosystems were evaluated. As a result of NAPAP funded research, negative effects of acidic deposition were documented on freshwater lakes in the Adirondacks and on the red spruce of the Adirondacks and northern Appalachians. One of the recommendations of the NAPAP Forest Response Program, however, was that a better understanding of the effects of acidic deposition and its constituents on processes within forest ecosystems was needed. In response to this need, the US Environmental Protection Agency (EPA) funded an ambitious program to manipulate the geochemical processes within wat- sheds in the United States. Originally, there were to be many watersheds to be treated, to encompass the scope of vegetation types, climate and deposition regimes. Ultimately only two such studies, one at on the Fernow Experimental Forest in West Virginia and one at Bear Brook Watersheds in Maine (BBWM) were implemented. Both are ongoing more than fifteen years later. Work began in 1987 in preparation for the Fernow Watershed Acidi- cation Study. Much attention was initially devoted to issues related to analyses of water chemistry and the quality control/quality assurance of the data coming from the study.

The Fernow Watershed Acidification Study

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Carbon Nanotubes: From Basic Research to Nanotechnology

The book comprises reviews on various topics of carbon nanotube research from specialists in the field, together with reports on on-going research. Both are intended to give a detailed picture of the remarkable properties of these one-dimensional nanostructures. Particular attention is paid to the synthesis, characterization, properties, and application of nanotubes. The book will be an indispensable introduction for the newcomers in the field as well as a valuable update for researchers in the field, for it contains the most recent developments.

Carbon Nanotubes: From Basic Research to Nanotechnology

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