International Telemetering Conference Proceedings / October 26-29, 1998 / Town & Country Resort Hotel and Convention Center, San Diego, California / The architecture of the High Rate (600 Mega-bits per second) Digital Demodulator (HRDD) ASIC capable of demodulating BPSK and QPSK modulated data is presented in this paper. The advantages of all-digital processing include increased flexibility and reliability with reduced reproduction costs. Conventional serial digital processing would require high processing rates necessitating a hardware implementation other than CMOS technology such as Gallium Arsenide (GaAs) which has high cost and power requirements. It is more desirable to use CMOS technology with its lower power requirements and higher gate density. However, digital demodulation of high data rates in CMOS requires parallel algorithms to process the sampled data at a rate lower than the data rate. The parallel processing algorithms described here were developed jointly by NASA’s Goddard Space Flight Center (GSFC) and the Jet Propulsion Laboratory (JPL). The resulting all-digital receiver has the capability to demodulate BPSK, QPSK, OQPSK, and DQPSK at data rates in excess of 300 Mega-bits per second (Mbps) per channel. This paper will provide an overview of the parallel architecture and features of the HRDR ASIC. In addition, this paper will provide an overview of the implementation of the hardware architectures used to create flexibility over conventional high rate analog or hybrid receivers. This flexibility includes a wide range of data rates, modulation schemes, and operating environments. In conclusion it will be shown how this high rate digital demodulator can be used with an off-the-shelf A/D and a flexible analog front end, both of which are numerically computer controlled, to produce a very flexible, low cost high rate digital receiver.

ITC/USA 2010 Conference Proceedings / The Forty-Sixth Annual International Telemetering Conference and Technical Exhibition / October 25-28, 2010 / Town and Country Resort & Convention Center, San Diego, California / In this article we present results from modeling and simulation of a L-band reflection type phase shifter (RTPS) that provides continuous phase shift of 0° to 360°. The RTPS circuit uses a 90º hybrid coupler and two reflective load networks consisting of varactor diodes and inductors. Proper design of 90° hybrid coupler is critical in realizing maximum phase shift. The RTPS circuit implemented on a Rogers Duroid substrate is large in size. We discuss methods to reduce the size of L-band RTPS.

Coral community at Tiaoshi in Nanwan Bay, southern Taiwan was originally dominated by branching Acropora corals which formed some monopolized patches. The community had been changed apparently on a local scale (<2 km) since 1994. Several Acropora patches were almost completely replaced by the solitary sea anemone Condylactis sp. after man-made and typhoon disturbances. However, sea anemones were apparently decreased in 2002. To understand the change of the benthic communities, three areas, including Anemone-dominated, Coral-recovery and Acropora-dominated, at depths of 6 to 10 m were selected and monitored by permanent transects from 2003 to 2005. Each site included three replicate patches. At Anemone-dominated area, the mean cover of sea anemone ranged from 24.6 to 15.3% and that of the hard corals was low with 1.4 to 3.9%. At Coral-recovery area, the mean cover of the hard corals was significantly increased from 21.3 to 38.9%, while macroalgae was significantly decreased from 20.7 to 6.1% and sea anemone was low with 1.4 to 3.0%. At Acropora-dominated area, the cover of the hard corals was ranged from 70.0 to 56.6% while macroalgae and anemone was 1.1 - 3.4% and 3.5 - 4.7%, respectively. In general, the results showed that anemone and macroalgae were decreased and corals were recovery. In addition, the diversity index of coral genera at Anemone-dominated area was higher due to coral recruitment in 2004 and 2005. The new recruits were dominated by Montipora stellata.

The development of a DC-DC converter for use in a proposed range of one to ten kilowatt off-line power supplies is presented. The converter makes good use of established design practices and recent technical advances. The thesis begins with a review of traditional design practices, which are used in the design of a 3kW, 48V output DC-DC converter, as a bench-mark for evaluation of recent technical advances. Advances evaluated include new converter circuits, control techniques, components, and magnetic component designs. Converter circuits using zero voltage switching (ZVS) transitions offer significant advantages for this application. Of the published converters which have ZVS transitions the phase shift controlled full bridge converter is the most suitable, and assessments of variations on this circuit are presented. During the course of the research it was realised that the ZVS range of one leg of the phase shift controlled full bridge converter could be extended by altering the switching pattern, and this new switching pattern is proposed. A detailed analysis of phase shift controlled full bridge converter operation uncovers a number of operational findings which give a better and more complete understanding of converter operation than hitherto published. Converter design equations and guidelines are presented and the effects of the new improvement are investigated by an approximate analysis. Computer simulations using PSPICE2 are carried out to predict converter performance. A prototype converter design, construction details and test results are given. The results obtained compare well to the predicted performance and confirm the advantages of the new switching pattern.

Thesis (M.S.)--Ohio University, June, 2002. / Title from PDF t.p. Includes bibliographical references (leaves 47-48).

Thesis (M.S. in Electrical Engineering) Naval Postgraduate School, March 1997. / Thesis advisors, Tri T. Ha, R. Clark Robertson. AD-A331 918. Includes bibliographical references (p. 69-70). Also available online.

In this letter, we propose all-dielectric Huygens' metasurface structures to construct high numerical aperture flat lenses and beam deflecting devices. The designed metasurface consists of two-dimensional array of all dielectric nanodisk resonators with spatially varying radii, thereby introducing judiciously designed phase shift to the propagating light. Owing to the overlap of Mie-type magnetic and electric resonances, high transmission was achieved with rigorous design analysis. The designed flat lenses have numerical aperture value of 0.85 and transmission values around 80%. It also offers easy fabrication and compatibility with available semiconductor technology. This spectrally and physically scalable, versatile design could implement efficient wavefront manipulation or beam shaping for high power laser beams, as well as various optical microscopy applications without requiring plasmonic structures that are susceptible to ohmic loss of metals and sensitive to the polarization of light.

Circadian clocks are responsible for scheduling many behavioral and physiological processes to occur at the most appropriate time of day. The resulting daily rhythms also synchronize (entrain) to external environmental cues, known as zeitgebers. This phenomenon of entrainment enables organisms to anticipate daily changes in environmental conditions such as sunrise/sunset, temperature variations, availability of prey, etc. Given the critical nature of entrainment to survival, it is no surprise that the mechanism is conserved across taxa. The misalignment of the intrinsic clock with the external environment results in a plethora of negative consequences, made apparent by studies involving shift work and jet lag. The focus of the present study is to investigate the chronobiology of Larinioides cornutus (Araneidae), a nocturnal orb-weaving spider, with an emphasis on its entrainment to light:dark cycles. Because spiders have received scarce attention with respect to their chronobiology, it is instructive to compare the properties of spider circadian systems with those of the more established circadian model systems, such as Drosophilaand Murines. We found that both lights-off and lights-on are equally influential zeitgeber cues for (determines the phasing of) both activity onset and offset. Locomotor activity typically begins within a half hour after nightfall, continues throughout the night, and ceases just prior to dawn. Phase shifting experiments show that these spiders can re-entrain within 2 days to a light/dark cycle shifted by 6 hours, and within 3 days when shifted by 12 hours. These rates of re-entrainment occur at an extremely accelerated rate compared to mammals, which readjust to a time shift at a rate of around 1 day/ 1 hour of phase shift. In other words, spiders have a minimal jet-lag response. This suggests an increased level of plasticity in the spider circadian clock that has yet to be observed in other organisms. Typical of circadian rhythms in nearly all organisms, activity also persisted (free-runs) under constant conditions. However, in constant darkness (DD), a drastic change in periodicity was revealed in 66% of individuals, from 23.4 to 25.2. This particular phenomenon is rare and likely indicates the possible interaction of multiple oscillators. Further evidence to support this interpretation is the consistent periods of the rhythm displayed before and after the change. In contrast, under constant light (LL) conditions, 65% of spiders were arrhythmic, with 4 individuals ceasing activity completely. Significant periods detected in LL were normally distributed over an unusually broad range, from 16.7 to 34.9 hours, suggesting a high sensitivity to light. Because of the unusual rates of re-entrainment to light/dark cycles, the spontaneous changes in free-running period under DD, and arrhythmicity in LL, we propose that spiders are valuable comparative model organism for elucidating fundamental mechanisms of circadian clocks.

The system diagrams for the digital radio compatible with NASA's S-Band Space Network operating from 2025.8 - 2117.9 MHz (forward link) to 2200 - 2300 MHz (return link) are presented. The digital radio implementation includes binary phase shift keying (BPSK), quadrature phase shift keying (QPSK) and staggered quadrature phase shift keying (SQPSK). We have derived the system requirements for these modulation schemes from the Space Network User Guide (SNUG) and thereafter, derived system diagrams for the communication links. The designed system diagrams for the transceiver were implemented using Simulink models and USRP2 platform.

ITC/USA 2007 Conference Proceedings / The Forty-Third Annual International Telemetering Conference and Technical Exhibition / October 22-25, 2007 / Riviera Hotel & Convention Center, Las Vegas, Nevada / This paper considers the use of Amplitude-Phase Shift Keying (APSK) for a telemetry system. Variable rate turbo codes are used to improve the power efficiency of 16- and 32-APSK. We discuss compensation techniques for power amplifier nonlinearities. Simulation results show the improved spectral efficiency of this modulation scheme over those currently defined in telemetry standards.