What are the environments, the public spaces, in which ordinary people become participants in the complex, ambiguous, engaging conversation about democracy: participators in governance rather than spectators or complainers, victims or accomplices? What are the roots, not simply of movements against oppression, but also of those democratic social movements which both enlarge the opportunities for participation and enhance people's ability to participate in the public world? In Free Spaces, Sara M. Evans and Harry C. Boyte argue for a new understanding of the foundations for democratic politics by analyzing the settings in which people learn to participate in democracy. In their new Introduction, the authors link the concept of free spaces to recent theoretical discussions about community, public life, civil society, and social movements.

In Spectral Properties of Certain Operators on a Free Hilbert Space and the Semicircular Law, the authors consider the so-called free Hilbert spaces, which are the Hilbert spaces induced by the usual l2 Hilbert spaces and operators acting on them. The construction of these operators itself is interesting and provides new types of Hilbert-space operators. Also, by considering spectral-theoretic properties of these operators, the authors illustrate how "free-Hilbert-space Operator Theory is different from the classical Operator Theory. More interestingly, the authors demonstrate how such operators affect the semicircular law induced by the ONB-vectors of a fixed free Hilbert space. Different from the usual approaches, this book shows how "inside actions of operator algebra deform the free-probabilistic information—in particular, the semicircular law. - Presents the spectral properties of three types of operators on a Hilbert space, in particular how these operators affect the semicircular law - Demonstrates how the semicircular law is deformed by actions "from inside", as opposed to actions "from outside" considered by previous theory - Explores free Hilbert spaces and their modeling applications - Authored by two leading researchers in Operator Theory and Operator Algebra

Annotation First book on Free Space Optics (FSO) in the marketplace. Comprehensive book that covers fundamentals through benefits and deployment pit falls. First comprehensive book about FSO, written by two experts in the field. Explores FSO as an alternative to cable and fiber as last-mile solutions. Enables readers to maximize the benefits of FSO and anticipate potential deployment pitfalls. Free Space Optics begins with the fundamentals of the technology before launching into FSO topologies, deployment issues, applications, and case studies. Baksheesh Ghuman is Vice President of Marketing at LightPointe Communications, Inc. Ghuman has worked in optical and telecommunications for over 12 years, focusing on marketing, product development, and applications engineering. He holds a Master of Science in Telecommunications Management from Golden State University, San Franscisco. Dr. Heinz Willebrand is Chief Technology Officer of LightPointe Communications where he leads all of LightPointe's R&D activities in the field of free space wireless RF and high-speed optical laser communication systems. Prior to LightPointe, Dr. Willebrand was a research professor at the University of Boulder, Colorado, where he taught classes on fiber optic and wireless technologies and researched areas such as fiber optics and high-speed computer interconnections.

This is a comprehensive tutorial on the emerging technology of free-space laser communications (FSLC). The book offers an all-inclusive source of information on the basics of FSLC, and a review of state-of-the-art technologies. Coverage includes atmospheric effects for laser propagation and FSLC systems performance and design. Free-Space Laser Communications is a valuable resource for engineers, scientists and students interested in laser communication systems designed for the atmospheric optical channel.

Free space optics is a telecommunications technique which is already being used for everyday exchange of information and has many advantages over other techniques (bandwidth, low cost, mobility of the equipment, security, etc.); within the next decade, it is likely to become an integral and essential part of data-processing architectures and telecommunications. A history of wireless optical telecommunications is given, together with a recapitulation of the application of the principles of electromagnetism to free-space optics. Coverage is also given to the transmitters and receivers of optical beams, whih are the basis of any optical communication system. These devices were responsible for the first truly significant advances in the performance of these systems. Special attention is given to the problems associated with the propagation of photons, both in the presence and absence of obstacles, since these are key issues in gaining an understanding of future telecommunication systems based on wireless optics. Finally, the authors considwer standards, as well as safety and confidentiality issues.

Recent progress in ICT has exceeded our expectations for meeting the requirement of multimedia society in the 21st century. The FSOC is considered to be one of the key technologies for realizing very high speed multi GbPs large-capacity terrestrial and aerospace communications. In FSOC, the optical beam propagation in the turbulent atmosphere is severely affected by various factors suspended in the channel. Wavefront aberration correcting with continuous beam alignment are the key requirements for a successful installation of an FSOC system which are the main contributions in our book. Establishment of FSOC setups, development of accurate weather station, measurement of atmospheric attenuation (Att) and turbulence strength (Cn2), development of new models to predict the Att and Cn2, design of Response Surface Model and Artificial Neural Network based on controller, implementation of neural-controller in FPGA and attaining the BER of 6.4x10^-9 during different outdoor environments. All the original contributions, newness, findings and experimental results etc., are reported in the book. Subject of work; Wireless Optical Communication. The content of the book can be referred by various application designers and/or academicians for working on FSOC transceiver design, laser cutting, laser metrology, laser surgery, beam focusing & pointing, beacon positioning and coupling etc. Further, all necessary MATLAB and VHDL codes are also given on appropriate pages for the readers' quick/ clear understanding.

This title provides a comprehensive, unified tutorial covering the most recent advances in the emerging technology of free-space optics (FSO), a field in which interest and attention continue to grow along with the number of new challenges. This book is intended as an all-inclusive source to serve the needs of those who require information about the fundamentals of FSO, as well as up-to-date advanced knowledge of the state-of-the-art in the technologies available today. This text is intended for graduate students, and will also be useful for research scientists and engineers with an interest in the field. FSO communication is a practical solution for creating a three dimensional global broadband communications grid, offering bandwidths far beyond what is possible in the Radio Frequency (RF) range. However, the attributes of atmospheric turbulence and scattering impose perennial limitations on availability and reliability of FSO links. From a systems point-of-view, this groundbreaking book provides a thorough understanding of channel behavior, which can be used to design and evaluate optimum transmission techniques that operate under realistic atmospheric conditions. Topics addressed include: • FSO Physical and Statistical Models: Single/Multiple Inputs/Outputs • Understanding FSO: Theory and Systems Analysis • Modulation and Coding for Free-Space Optical Channels • Atmospheric Mitigation and Compensation for FSO Links • Non-line-of-sight (NLOS) Ultraviolet and Indoor FSO Communications • FSO Platforms: UAV and Mobile • Retromodulators for Free Space Data links • Hybrid Optical RF Communications • Free-space and Atmospheric Quantum Communications • Other related topics: Chaos-based and Terahertz (THz) FSO Communications

This book provides an in-depth understanding of free space optical (FSO) communication with a particular emphasis on optical beam propagation through atmospheric turbulence. The book is structured in such a way that it provides a basic framework for the beginners and also gives a concise description from a designer’s perspective. The book provides an exposure to FSO technology, fundamental limitations, design methodologies, system trade-offs, acquisition, tracking and pointing (ATP) techniques and link-feasibility analysis. The contents of this book will be of interest to professionals and researchers alike. The book may also be used as a textbook for engineering coursework and professional training.

An analysis is presented whereby the free-space oscillating pressures associated with a rotating propeller may be determined at any point in space. This analysis is based on the fundamental Gutin equations without some of the simplifying assumptions. Static tests for several different propellers were conducted in the tip Mach number rang 0.45 to 1.00. Charts are given for estimating free-space pressures for a given propeller. The response of the fuselage to these oscillating pressures is also treated and some factors to be considered in solving the problems of fuselage vibration and noise are indicated.