by Yue Ping Zhang. / Publication date from spine. / Thesis (Ph.D.)--Chinese University of Hong Kong, 1995. / Includes bibliographical references (leaves 194-200). / DEDICATION / ACKNOWLEDGMENTS / Chapter / Chapter 1. --- Introduction --- p.1 / Chapter 1.1 --- Brief Description of Tunnels --- p.1 / Chapter 1.2 --- Review of Tunnel Imperfect Waveguide Models --- p.2 / Chapter 1.3 --- Review of Tunnel Geometrical Optical Model --- p.4 / Chapter 1.4 --- Review of Tunnel Propagation Experimental Results --- p.6 / Chapter 1.5 --- Review of Existing Tunnel UHF Radio Communication Systems --- p.13 / Chapter 1.6 --- Statement of Problems to be Studied --- p.15 / Chapter 1.7 --- Organization --- p.15 / Chapter 2 --- Propagation in Empty Tunnels --- p.18 / Chapter 2.1 --- Introduction --- p.18 / Chapter 2.2 --- Propagation in Empty Tunnels --- p.18 / Chapter 2.2.1 --- The Imperfect Empty Straight Rectangular Waveguide Model --- p.19 / Chapter 2.2.2 --- The Hertz Vectors for Empty Straight Tunnels --- p.20 / Chapter 2.2.3 --- The Propagation Modal Equations for Empty Straight Tunnels --- p.23 / Chapter 2.2.4 --- The Propagation Characteristics of Empty Straight Tunnels --- p.26 / Chapter 2.2.5 --- Propagation Numerical Results in Empty Straight Tunnels --- p.30 / Chapter 2.3 --- Propagation in Empty Curved Tunnels --- p.36 / Chapter 2.3.1 --- The Imperfect Empty Curved Rectangular Waveguide Model --- p.37 / Chapter 2.3.2 --- The Hertz Vectors for Empty Curved Tunnels --- p.39 / Chapter 2.3.3 --- The Propagation Modal Equations for Empty Curved Tunnels --- p.41 / Chapter 2.3.4 --- The Propagation Characteristics of Empty Curved Tunnels --- p.43 / Chapter 2.2.5 --- Propagation Numerical Results in Empty Curved Tunnels --- p.47 / Chapter 2.4 --- Summary --- p.50 / Chapter 3 --- Propagation in Occupied Tunnels --- p.53 / Chapter 3.1 --- Introduction --- p.53 / Chapter 3.2 --- Propagation in Road Tunnels --- p.53 / Chapter 3.2.1 --- The Imperfect Partially Filled Rectangular Waveguide Model --- p.54 / Chapter 3.2.2 --- The Scalar Potentials for Road tunnels --- p.56 / Chapter 3.2.3 --- The Propagation Modal Equations for Road Tunnels --- p.59 / Chapter 3.2.4 --- Propagation Numerical Results in Road Tunnels --- p.61 / Chapter 3.3 --- Propagation in Railway Tunnels --- p.64 / Chapter 3.3.1 --- The Imperfect Periodically Loaded Rectangular Waveguide Model --- p.65 / Chapter 3.3.2 --- The Surface Impedance Approximation --- p.66 / Chapter 3.3.2.1 --- The Surface Impedance of a Semi-infinite Lossy Dielectric Medium --- p.66 / Chapter 3.3.2.2 --- The Surface Impedance of a Thin Lossy Dielectric Slab --- p.67 / Chapter 3.3.2.3 --- The Surface Impedance of a Three-layered Half Space --- p.69 / Chapter 3.3.2.4 --- The Surface Impedance of the Sidewall of a Train in a Tunnel --- p.70 / Chapter 3.3.3 --- The Hertz Vectors for Railway Tunnels --- p.71 / Chapter 3.3.4 --- The Propagation Modal Equations for Railway Tunnels --- p.73 / Chapter 3.3.5 --- The Propagation Characteristics of Railway Tunnels --- p.76 / Chapter 3.3.6 --- Propagation Numerical Results in Railway Tunnels --- p.78 / Chapter 3.4 --- Propagation in Mine Tunnels --- p.84 / Chapter 3.4.1 --- The Imperfect periodically Loaded Rectangular Waveguide Model --- p.85 / Chapter 3.4.2 --- The Hertz Vectors for Mine Tunnels --- p.86 / Chapter 3.4.3 --- The Propagation modal Equations for Mine Tunnels --- p.88 / Chapter 3.4.4 --- The Propagation Characteristics of Mine Tunnels --- p.95 / Chapter 3.4.5 --- Propagation Numerical Results in Mine Tunnels --- p.96 / Chapter 3.5 --- Summary --- p.97 / Chapter 4 --- Statistical and Deterministic Models of Tunnel UHF Propagation --- p.100 / Chapter 4.1 --- Introduction --- p.100 / Chapter 4.2 --- Statistical Model of Tunnel UHF Propagation --- p.100 / Chapter 4.2.1 --- Experiments --- p.101 / Chapter 4.2.1.1 --- Experimental Set-ups --- p.102 / Chapter 4.2.1.2 --- Experimental Tunnels --- p.104 / Chapter 4.2.1.3 --- Experimental Techniques --- p.106 / Chapter 4.2.2 --- Statistical Parameters --- p.109 / Chapter 4.2.2.1 --- Parameters to Characterize Narrow Band Radio Propagation Channels --- p.109 / Chapter 4.2.2.2 --- Parameters to Characterize Wide Band Radio Propagation Channels --- p.111 / Chapter 4.2.3 --- Propagation Statistical Results and Discussion --- p.112 / Chapter 4.2.3.1 --- Tunnel Narrow Band Radio Propagation Characteristics --- p.112 / Chapter 4.2.3.1.1 --- Power Distance Law --- p.114 / Chapter 4.2.3.1.2 --- The Slow Fading Statistics --- p.120 / Chapter 4.2.3.1.3 --- The Fast Fading Statistics --- p.122 / Chapter 4.2.3.2 --- Tunnel Wide Band Radio Propagation Characteristics --- p.125 / Chapter 4.2.3.2.1 --- RMS Delay Spread --- p.126 / Chapter 4.2.3.2.2 --- RMS Delay Spread Statistics --- p.130 / Chapter 4.3 --- Deterministic Model of Tunnel UHF Propagation --- p.132 / Chapter 4.3.1 --- The Tunnel Geometrical Optical Propagation Model --- p.134 / Chapter 4.3.2 --- The Tunnel Impedance Uniform Diffracted Propagation Model --- p.141 / Chapter 4.3.2.1 --- Determination of Diffraction Points --- p.146 / Chapter 4.3.2.2 --- Diffraction Coefficients for Impedance Wedges --- p.147 / Chapter 4.3.3 --- Comparison with Measurements --- p.151 / Chapter 4.3.3.1 --- Narrow Band Comparison of Simulated and Measured Results --- p.151 / Chapter 4.3.3.1.1 --- Narrow Band Propagation in Empty Straight Tunnels --- p.151 / Chapter 4.3.3.1.2 --- Narrow Band Propagation in Curved or Obstructed Tunnels --- p.154 / Chapter 4.3.3.2 --- Wide Band Comparison of Simulated and Measured Results --- p.158 / Chapter 4.3.3.2.1 --- Wide Band Propagation in Empty Straight Tunnels --- p.159 / Chapter 4.3.3.2.2 --- Wide Band Propagation in an Obstructed Tunnel --- p.163 / Chapter 4.4 --- Summary --- p.165 / Chapter 5 --- Propagation in Tunnel and Open Air Transition Region --- p.170 / Chapter 5.1 --- Introduction --- p.170 / Chapter 5.2 --- Radiation of Radio Waves from a Rectangular Tunnel into Open Air --- p.171 / Chapter 5.2.1 --- Radiation Formulation Using Equivalent Current Source Concept --- p.171 / Chapter 5.2.2 --- Radiation Numerical Results --- p.175 / Chapter 5.3 --- Propagation Characteristics of UHF Radio Waves in Cuttings --- p.177 / Chapter 5.3.1 --- The Attenuation Constant due to the Absorption --- p.178 / Chapter 5.3.2 --- The Attenuation Constant due to the Roughness of the Sidewalls --- p.182 / Chapter 5.3.3 --- The Attenuation Constant due to the tilts of the Sidewalls --- p.183 / Chapter 5.3.4 --- Propagation Numerical Results in Cuttings --- p.184 / Chapter 5.4 --- Summary --- p.187 / Chapter 6 --- Conclusion and Recommendation for Future Work --- p.189 / APPENDIX --- p.193 / The Approximate Solution of a Transcendental Equation --- p.193 / REFERENCES --- p.194

by Lee Wai Hung. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1999. / Includes bibliographical references (leaves 118-121). / Abstracts in English and Chinese. / Chapter 1 --- INTRODUCTION --- p.1 / Chapter 1.1 --- Background --- p.1 / Chapter 1.2 --- Structure of Thesis --- p.8 / Chapter 1.3 --- Methodology --- p.8 / Chapter 2 --- BACKGROUND THEORY --- p.10 / Chapter 2.1 --- Radio Wave Propagation Modeling --- p.10 / Chapter 2.1.1 --- Basic Propagation Phenomena --- p.10 / Chapter 2.1.1.1 --- Propagation in Free Space --- p.10 / Chapter 2.1.1.2 --- Reflection and Transmission --- p.11 / Chapter 2.1.2 --- Practical Propagation Models --- p.12 / Chapter 2.1.2.1 --- Longley-Rice Model --- p.13 / Chapter 2.1.2.2 --- The Okumura Model --- p.13 / Chapter 2.1.3 --- Indoor Propagation Models --- p.14 / Chapter 2.1.3.1 --- Alexander Distance/Power Laws --- p.14 / Chapter 2.1.3.2 --- Saleh Model --- p.15 / Chapter 2.1.3.3 --- Hashemi Experiments --- p.16 / Chapter 2.1.3.4 --- Path Loss Models --- p.17 / Chapter 2.1.3.5 --- Ray Optical Models --- p.18 / Chapter 2.2 --- Ray Tracing： Brute Force approach --- p.20 / Chapter 2.2.1 --- Physical Layout --- p.20 / Chapter 2.2.2 --- Antenna Information --- p.20 / Chapter 2.2.3 --- Source Ray Directions --- p.21 / Chapter 2.2.4 --- Formulation --- p.22 / Chapter 2.2.4.1 --- Formula of Amplitude --- p.22 / Chapter 2.2.4.2 --- Power Reference E o --- p.23 / Chapter 2.2.4.3 --- Power spreading with path length 1/d --- p.23 / Chapter 2.2.4.4 --- Antenna Patterns --- p.23 / Chapter 2.2.4.5 --- Reflection and Transmission Coefficients --- p.24 / Chapter 2.2.4.6 --- Polarization --- p.26 / Chapter 2.2.5 --- Mean Received Power --- p.26 / Chapter 2.2.6 --- Effect of Thickness --- p.27 / Chapter 2.3 --- Neural Network --- p.27 / Chapter 2.3.1 --- Architecture --- p.28 / Chapter 2.3.1.1 --- Multilayer feedforward network --- p.28 / Chapter 2.3.1.2 --- Recurrent Network --- p.29 / Chapter 2.3.1.3 --- Fuzzy ARTMAP --- p.29 / Chapter 2.3.1.4 --- Self organization map --- p.30 / Chapter 2.3.1.5 --- Modular Neural network --- p.30 / Chapter 2.3.2 --- Training Method --- p.32 / Chapter 2.3.3 --- Advantages --- p.33 / Chapter 2.3.4 --- Definition --- p.34 / Chapter 2.3.5 --- Software --- p.34 / Chapter 3 --- HYBRID MODULAR NEURAL NETWORK --- p.35 / Chapter 3.1 --- Input and Output Parameters --- p.35 / Chapter 3.2 --- Architecture --- p.36 / Chapter 3.3 --- Data Preparation --- p.42 / Chapter 3.4 --- Advantages --- p.42 / Chapter 3.5 --- Limitation --- p.43 / Chapter 3.6 --- Applicable Environment --- p.43 / Chapter 4 --- INDIVIDUAL MODULES IN HYBRID MODULAR NEURAL NETWORK --- p.45 / Chapter 4.1 --- Conversion between spherical coordinate and Cartesian coordinate --- p.46 / Chapter 4.1.1 --- Architecture --- p.46 / Chapter 4.1.2 --- Input and Output Parameters --- p.47 / Chapter 4.1.3 --- Testing result --- p.48 / Chapter 4.2 --- Performing Rotation and translation transformation --- p.53 / Chapter 4.3 --- Calculating a hit point --- p.54 / Chapter 4.3.1 --- Architecture --- p.55 / Chapter 4.3.2 --- Input and Output Parameters --- p.55 / Chapter 4.3.3 --- Testing result --- p.56 / Chapter 4.4 --- Checking if an incident ray hits a Scattering Surface --- p.59 / Chapter 4.5 --- Calculating separation distance between source point and hitting point --- p.59 / Chapter 4.5.1 --- Input and Output Parameters --- p.60 / Chapter 4.5.2 --- Data Preparation --- p.60 / Chapter 4.5.3 --- Testing result --- p.61 / Chapter 4.6 --- Calculating propagation vector of secondary ray --- p.63 / Chapter 4.7 --- Calculating polarization vector of secondary ray --- p.63 / Chapter 4.7.1 --- Architecture --- p.64 / Chapter 4.1.2 --- Input and Output Parameters --- p.65 / Chapter 4.7.3 --- Testing result --- p.68 / Chapter 4.8 --- Rejecting ray from simulation --- p.72 / Chapter 4.9 --- Calculating receiver signal --- p.73 / Chapter 4.10 --- Further comment on preparing neural network --- p.74 / Chapter 4.10.1 --- Data preparation --- p.74 / Chapter 4.10.2 --- Batch training --- p.75 / Chapter 4.10.3 --- Batch size --- p.78 / Chapter 5 --- CANONICAL EVALUATION OF MODULAR NEURAL NETWORK --- p.80 / Chapter 5.1 --- Typical environment simulation compared with ray launching --- p.80 / Chapter 5.1.1 --- Free space --- p.80 / Chapter 5.1.2 --- Metal ground reflection --- p.81 / Chapter 5.1.3 --- Dielectric ground reflection --- p.84 / Chapter 5.1.4 --- Empty Hall --- p.86 / Chapter 6 --- INDOOR PROPAGATION ENVIRONMENT APPLICATION --- p.90 / Chapter 6.1 --- Introduction --- p.90 / Chapter 6.2 --- Indoor measurement on the Third Floor of Engineering Building --- p.90 / Chapter 6.3 --- Comparison between simulation and measurement result --- p.92 / Chapter 6.3.1 --- Path 1 --- p.93 / Chapter 6.3.2 --- Path 2 --- p.95 / Chapter 6.3.3 --- Path 3 --- p.97 / Chapter 6.3.4 --- Path 4 --- p.99 / Chapter 6.3.5 --- Overall Performance --- p.100 / Chapter 6.4 --- Delay Spread Analysis --- p.101 / Chapter 6.4.1 --- Location 1 --- p.103 / Chapter 6.4.2 --- Location 2 --- p.105 / Chapter 6.4.3 --- Location 3 --- p.107 / Chapter 6.4.4 --- Location 4 --- p.109 / Chapter 6.4.5 --- Location 5 --- p.111 / Chapter 6.5 --- Summary --- p.112 / Chapter 7 --- CONCLUSION --- p.I / Chapter 7.1 --- Summary --- p.113 / Chapter 7.2 --- Recommendations for Future Work --- p.115 / PUBLICATION LIST --- p.117 / BIBLIOGRAHY --- p.118

<p>Militära insatser i urban miljö kommer troligen att öka alltmer. Detta kräver soldater till fots eftersom dessa lättare kan förflytta sig via och mellan byggnader. Varje deltagande soldat kommer att behöva egen radioutrustning. Då stadsmiljö är ett relativt outforskat område vad gäller militär radiokommunikation är det viktigt att öka förståelsen för radiovågors utbredning i stadsmiljö. Härtill har institutionen för Informationsöverföring på FOI köpt in programmet Radiowave Propagation Simulator (RPS). RPS används i det här examensarbetet för att genomföra en beräkning för ett statiskt scenario, och till beräkningen infoga påverkan från sändares och</p><p>mottagares mobilitet. Detta utförs genom att rumsligt extrapolera kanalens impulssvar till att gälla i andra positioner än de ursprungligen var beräknade för. Kanalens impulssvar blir då modifierat så att impulssvarets utbredningsvägar får nya fördröjningstider och dess komplexa signal får ny fas.</p><p>Metoden, som har tagits fram i det här arbetet, för den rumsliga extrapoleringen har implementerats och utvärderats för ett litet scenario. Det extrapolerade resultatet har sedan jämförts med beräknade resultat från RPS. Analysen visade att metoden ger ett tillförlitligt resultat. Ett annat syfte med examensarbetet har varit att visa hur forskningsresultat (från radiokanalen) kan användas effektivare för att ge högre kvalité på forskningsresultat, både på länk- och på nätnivå.</p>

"November 15, 1962." "Submitted to the Department of Electrical Engineering, M.I.T., January 15, 1962, in partial fulfillment of the requirements for the degree of Master of Science." / Bibliography: p. 75-76. / Army Signal Corps Contract No. DA 36-039-sc-78108. Dept. of the Army Project No. 3-99-20-001 Project 3-99-00-000. Army Signal Corps Contract No. DA-SIG-36-039-61-G14.

Militära insatser i urban miljö kommer troligen att öka alltmer. Detta kräver soldater till fots eftersom dessa lättare kan förflytta sig via och mellan byggnader. Varje deltagande soldat kommer att behöva egen radioutrustning. Då stadsmiljö är ett relativt outforskat område vad gäller militär radiokommunikation är det viktigt att öka förståelsen för radiovågors utbredning i stadsmiljö. Härtill har institutionen för Informationsöverföring på FOI köpt in programmet Radiowave Propagation Simulator (RPS). RPS används i det här examensarbetet för att genomföra en beräkning för ett statiskt scenario, och till beräkningen infoga påverkan från sändares och mottagares mobilitet. Detta utförs genom att rumsligt extrapolera kanalens impulssvar till att gälla i andra positioner än de ursprungligen var beräknade för. Kanalens impulssvar blir då modifierat så att impulssvarets utbredningsvägar får nya fördröjningstider och dess komplexa signal får ny fas. Metoden, som har tagits fram i det här arbetet, för den rumsliga extrapoleringen har implementerats och utvärderats för ett litet scenario. Det extrapolerade resultatet har sedan jämförts med beräknade resultat från RPS. Analysen visade att metoden ger ett tillförlitligt resultat. Ett annat syfte med examensarbetet har varit att visa hur forskningsresultat (från radiokanalen) kan användas effektivare för att ge högre kvalité på forskningsresultat, både på länk- och på nätnivå.

Predicting performance metrics for the next-generation of multi-mode and multi-antenna wireless communication systems demands site-specific knowledge of the wireless channel's underlying radio wave propagation mechanisms. This thesis describes the first measurement system capable of characterizing individual propagation mechanisms in situ. The measurement system merges a high-resolution spatio-temporal wireless channel sounder with a new field reconstruction technique to provide complete knowledge of the wireless channel's impulse response throughout a 2-dimensional region. This wealth of data may be combined with space-time filtering techniques to isolate and characterize individual propagation mechanisms. The utility of the spatio-temporal measurement system is demonstrated through a measurement-based investigation of diffraction around building corners. These measurements are combined with space-time filtering techniques and a new linear wedge diffraction model to extract the first semi-mpirical diffraction coefficient. Specific contributions of this thesis are: * The first ultra-wideband single-input multiple-output (SIMO) channel sounder based upon the sliding correlator architecture. * A quasi 2-dimensional field reconstruction technique based upon a conjoint cylindrical wave expansion of coherent perimeter measurements. * A wireless channel ``filming' technique that records the time-domain evolution of the wireless channel throughout a 2-dimensional region. * High-resolution measurements of the space-time wireless channel near a right-angled brick building corner. * The application of space-time filtering techniques to isolate the edge diffraction problem from the overall wireless channel. * An approximate uniform geometrical theory of diffraction (UTD)-style linear model describing diffraction by an impedance wedge. * The first-ever semi-empirical diffraction coefficient extracted from in situ measurement data. This thesis paves the way for several new avenues of research. The comprehensive measurement data provided by channel "filming" will enable researchers to develop and implement powerful space-time filtering techniques that facilitate measurement-based investigations of radio wave propagation. The measurement procedure described in this thesis may be adapted to extract realistic reflection and rough-surface scattering coefficients. Finally, exhaustive measurements of individual propagation mechanisms will enable the first semi-empirical propagation model that integrates empirical descriptions of propagation mechanisms into a UTD-style mechanistic framework.

Thesis (M.S.)--Brigham Young University. Dept. of Electrical and Computer Engineering, 2004. / Includes bibliographical references (p. 145-154).

Not available / text

Several previous studies, including one using early Sanae radar data, have found examples of high speed ionospheric plasma flows on the nightside, mapping to the magnetospheric tail, during periods which were magnetically quiet. These high speed flows were interpreted to be associated with the release of energy from a rapid reconfiguration of tail magnetic field lines due to reconnection. Such events are now known as ‘TRINNIs’ or ‘tail reconnection during IMF northward, non-substorm intervals’. The purpose of this study was to identify further TRINNI events, using SuperDARN data from both hemispheres. In situations where the y-component of the Interplanetary Magnetic Field dominates over the z-component, the directions of both the high speed flows and the underlying convection pattern depend on the direction of the y-component. Some examples of likely TRINNI events for cases where the y-component was positive and negative are presented and discussed. The assumption of a non-substorm interval is justified by magnetometer and GOES satellite data, and the observations are discussed in relation to magnetic reconnection in the magnetotail. / Thesis (M.Sc.)-University of KwaZulu-Natal, Westville, 2010.

The performance of astronomical interferometer arrays operating at (sub) millimeter wave-lengths is seriously compromised by rapid variations of atmospheric water vapour content that distort the phase coherence of incoming celestial signals. Unless corrected, these phase distortions, which vary rapidly with time and from antenna to antenna, seriously compromise the sensitivity and image quality of these arrays. Building on the success of a prototype infrared radiometer for millimeter astronomy (IRMA I), which was ued to measure atmospheric water vapour column abundance, this thesis presents results from a second generation radiometer (IRMA II) operating at the James Clerk Maxwell Telescope (JCMT) on Mauna Kea, Hawaii from December, 2000 to March, 2001. These results include comparisons with other measures of water vapour abundance available on the summit of Mauna Kea and a comparison with a theorteical curve-of-growth calculated from a new radiative transfer model, ULTRAM, developed specifically for the purpose. Plans for a third generation radiometer (IRMA III) are also be discussed. / xii, 143 leaves : ill. ; 28 cm.