Global ETD Search

31	LOW COST SUBMINIATURE TELEMETRY SPREAD SPECTRUM TECHNOLOGY DEMONSTRATION/VALIDATION Thursby, William R. Jr, Shirley, Benjamin M. 11 1900 (has links) International Telemetering Conference Proceedings / October 30-November 02, 1995 / Riviera Hotel, Las Vegas, Nevada / Eglin Air Force Base (AFB) plans to demonstrate subminiature telemetry (SMT) spread spectrum technology, via an upgraded prototype SMT system, to validate its cost-effectiveness for both Department of Defense (DoD) and commercial use. The goal is to develop new and/or modify current SMT instrumentation using existing production methods to provide increased capabilities at lower costs and reduced size. The transmitter is to require less than 2 cubic inches of space and have a cost goal of $500/unit "in quantity." The cost goal of a ground-based, 24-channel capable ground receiver is $4000/unit "in quantity". The SMT project as well as its schedule, flight and ground demonstrations, validation criteria and goals, and various benefits are discussed. Subminiature Telemetry Spread Spectrum Integrated Telemetry Package Receiver/Demodulator Unit Airborne Receiver/Demodulator Unit Upper S-Band Test Technology Demonstration/Validation Low Cost Dual Use
32	A thiophene backbone enables two‐dimensional poly(arylene vinylene)s with high charge carrier mobility Liu, Yamei, Heng, Yu, Hongde, Liao, Zhongquan, Paasch, Silvia, Xu, Shunqi, Zhao, Ruyan, Brunner, Eike, Bonn, Mischa, Wang, Hai I., Heine, Thomas, Wang, Mingchao, Mai, Yiyong, Feng, Xinliang 24 January 2024 (has links) Linear conjugated polymers have attracted significant attention in organic electronics in recent decades. However, despite intrachain π-delocalization, interchain hopping is their transport bottleneck. In contrast, two-dimensional (2D) conjugated polymers, as represented by 2D π-conjugated covalent organic frameworks (2D c-COFs), can provide multiple conjugated strands to enhance the delocalization of charge carriers in space. Herein, we demonstrate the first example of thiophene-based 2D poly(arylene vinylene)s (PAVs, 2DPAV-BDT-BT and 2DPAV-BDT-BP, BDT=benzodithiophene, BT=bithiophene, BP=biphenyl) via Knoevenagel polycondensation. Compared with 2DPAV-BDT-BP, the fully thiophene-based 2DPAV-BDT-BT exhibits enhanced planarity and π-delocalization with a small band gap (1.62 eV) and large electronic band dispersion, as revealed by the optical absorption and density functional calculations. Remarkably, temperature-dependent terahertz spectroscopy discloses a unique band-like transport and outstanding room-temperature charge mobility for 2DPAV-BDT-BT (65 cm2 V−1 s−1), which far exceeds that of the linear PAVs, 2DPAV-BDT-BP, and the reported 2D c-COFs in the powder form. This work highlights the great potential of thiophene-based 2D PAVs as candidates for high-performance opto-electronics. info:eu-repo/classification/ddc/540 ddc:540
33	Radio Wave Propagation Measurements and Modeling for Land Mobile Satellite Systems Mousselon, Laure 09 December 2002 (has links) The performance of a mobile satellite communications link is conditioned by the characteristics of the propagation path between a satellite and mobile users. The most important propagation effect in land mobile satellite system is roadside attenuation of the signals due to vegetation or urban structures. System designers should have the most reliable information about the statistics of the propagation channel to build reliable systems that can compensate for bad propagation conditions. In 1998, the Virginia Tech Antenna Group developed a simulator, PROSIM, to simulate a propagation channel in the case of roadside tree attenuation in land mobile satellite systems. This thesis describes some improvements to PROSIM, and the adaptation and validation of PROSIM for Digital Audio Radio Satellite systems operating at S-band frequencies. The performance of the simulator for S-band frequencies was evaluated through a measurement campaign conducted with the XM Radio signals at 2.33 GHz in various propagation environments. Finally, additional results on dual satellite systems and fade correlation are described. / Master of Science Cumulative Fade Distribution Measurements Lognormal LMSS S-band Propagation Model DARS Shadowing Propagation Simulator Average Fade Duration Level Crossing Rate Rayleigh Ricean Dual Satellites
34	Design and Heterogeneous Integration of Single and Dual Band Pulse Modulated Class E RF Power Amplifiers Rashid, S M Shahriar January 2018 (has links) No description available. Electrical Engineering Switched Mode, Class E Power Amplifier PA SMPA CML Driver Buffer Wideband RF Integrated Circuit IC Heterogeneous Compound Semiconductor Heterojunction III-V GaAs GaN CMOS pHEMT Pulse Modulator PWM PPM Transformer S band C band GHz

Page generated in 0.0351 seconds