The high and ever growing demand for electricity coupled with environmental concerns and a worldwide desire to shed petroleum dependence, all point to a shift to utilization of renewable sources of energy. The under developed nature of truly renewable energy sources such as, wind and solar, along with their limitations on the areas of applicability and the energy output calls for a renaissance in nuclear energy. In this second nuclear era, deliberately small reactors are poised to play a major role with a number of Small Modular Reactors (SMRs) currently under development in the U.S. In this work, an SMR model of the Integral Pressurized Water Reactor (IPWR) type is created, analyzed and optimized to meet the publically available performance criteria of the mPower SMR from B&W. The Monte Carlo codes MCNP5/MCNPX are used to model the core. Fuel enrichment, core inventory, core size are all variables optimized to meet the set goals of core lifetime and fuel utilization (burnup). Vital core behavior characteristics such as delayed neutron fraction and reactivity coefficients are calculated and shown to be typical of larger PWR systems, which is necessary to ensure the inherent safety and to achieve rapid deployment of the reactor by leveraging the vast body of operational experience amassed with the larger commercial PWRs. Inherent safety of the model is analyzed with the results of an analytical single channel analysis showing promising behavior in terms of axial and radial fuel element temperature distributions, the critical heat flux, and the departure from nucleate boiling ratio. The new fleet of proposed SMRs is intended to have increased proliferation resistance (PR) compared to the existing fleet of operating commercial PWRs. To quantify this PR gain, a PR analysis is performed using the Proliferation Resistance Analysis and Evaluation Tool for Observed Risk (PRAETOR) code developed by the Nuclear Science and Security Policy Institute at Texas A&M University. The PRAETOR code uses multi-attribute utility analysis to combine 63 factors affecting the PR value of a facility into a single metric which is easily comparable. The analysis compared hypothetical spent fuel storage facilities for the SMR model spent fuel assembly and one for spent fuel from a Westinghouse AP1000. The results showed that from a fuel material standpoint, the SMR and AP1000 had effectively the same PR value. Unable to analyze security systems and methods employed at specific nuclear power plant sites, it is premature to conclude that the SMR plants will not indeed show increased PR as intended.

Les signaux multicanaux sont des signaux captés à travers plusieurs canaux ou capteurs, portant chacun un mélange de sources, une partie desquelles est connue alors que le reste des sources reste inconnu. Les méthodes à l’aide desquelles l’isolement ou la séparation des sources est accomplie sont connues par les méthodes de séparation de sources en général, et si le degré d’inconnu est large, par la séparation aveugle des sources (SAS). Cependant, la SAS appliquée aux signaux multicanaux est en fait plus facile de point de vue mathématique que l’application de la SAS sur des signaux monocanaux, ou un seul capteur existe et tous les signaux arrivent au même point pour enfin produire un mélange de sources inconnues. Tel est le domaine de cette thèse. Nous avons développé une nouvelle technique de SAS : une combinaison de plusieurs méthodes de séparation et d’optimisation, basée sur la factorisation non-négative des matrices (NMF). Cette méthode peut être utilisée dans de nombreux domaines comme l’analyse des sons et de la parole, les variations de la bourse, et les séismographes. Néanmoins, ici, les signaux de force de réaction de terre verticaux (VGRF) monocanaux d’un groupe d’athlètes coureurs d’ultra-marathon sont analysés et séparés pour l’extraction du peak passif du peak actif d’une nouvelle manière adaptée à la nature de ces signaux. Les signaux VGRF sont des signaux cyclo-stationnaires caractérisés par des double-peaks, chacun étant très rapide et parcimonieux, indiquant les phases de course de l’athlète. L’analyse des peaks est extrêmement importante pour déterminer et prédire la condition du coureur : problème physiologique, problème anatomique, fatigue etc. De plus, un grand nombre de chercheurs ont prouvé que l’impact du pied postérieur avec la terre d’une manière brutale, l’analyse de ce phénomène peut nous ramener à une prédiction de blessure interne. Ils essayent même d’adopter une technique de course - Non-Heel-strike Running (NHS) - par laquelle ils obligent les coureurs à courir sur le pied-antérieur seulement. Afin d'étudier ce phénomène, la séparation du peak d’impact du VGRF permet d'isoler la source portant les informations patho-physiologiques et le degré de fatigue. Nous avons introduit de nouvelles méthodes de prétraitement et de traitement des signaux VGRF pour remplacer le filtrage de bruit traditionnel utilisé partout, et qui peut parfois détruire les peaks d’impact qui sont nos sources à séparer, base sur le concept de soustraction spectrale pour le filtrage, utilisée avec les signaux de parole, après l’application d’un algorithme d’échantillonnage intelligent et adaptatif qui décompose les signaux en pas isolés. Une analyse des signaux VGRF en fonction du temps a été faite pour la détection et la quantification de la fatigue des coureurs durant les 24 heures de course. Cette analyse a été accomplie au domaine fréquentiel/spectral où nous avons détecté un décalage clair du contenu fréquentiel avec la progression de la course indiquant la progression de la fatigue. Nous avons défini les signaux cyclosparse au domaine temporel, puis traduit cette définition à son équivalent au domaine temps-fréquence utilisant la transformée Fourier a court-temps (STFT). Cette représentation a été décomposée à travers une nouvelle méthode que l’on a appelé Cyclosparse Non-negative Matrix Factorisation (Cyclosparse-NMF), basée sur l’optimisation de la minimisation de la divergence Kullback-Leibler (KL) avec pénalisation liée à la périodicité et la parcimonie des sources, ayant comme but final d’extraire les sources cyclosparse du mélange monocanal appliquée aux signaux VGRF monocanaux. La méthode a été testée sur des signaux analytiques afin de prouver l’efficacité de l’algorithme. Les résultats se sont avéré satisfaisants, et le peak impact a été séparé du mélange VGRF monocanal. / The purpose of the presented work is to develop a customized Single-channel Blind Source Separation technique that aims to separate cyclostationary and transient pulse-like patterns/sources from a linear instantaneous mixture of unknown sources. For that endeavor, synthetic signals of the mentioned characteristic were created to confirm the separation success, in addition to real life signals acquired throughout an experiment in which experienced athletes were asked to participate in a 24-hour ultra-marathon in a lab environment on an instrumented treadmill through which their VGRF, which carries a cyclosparse Impact Peak, is continuously recorded with very short discontinuities during which blood is drawn for in-run testing, short enough not to provide rest to the athletes. The synthetic and VGRF signals were then pre-processed, processed for Impact Pattern extraction via a customized Single-channel Blind Source Separation technique that we termed Cyclo-sparse Non-negative Matrix Factorization and analyzed for fatigue assessment. As a result, the Impact Patterns for all of the participating athletes were extracted at 10 different time intervals indicating the progression of the ultra-marathon for 24 hours, and further analysis and comparison of the resulting signals proved major significance in the field of fatigue assessment; the Impact Pattern power monotonically increased for 90% of the subjects by an average of 24.4 15% with the progression of the ultra-marathon during the 24-hour period. Upon computation of the Impact Pattern separation algorithm, fatigue progression showed to be manifested by an increase in reliance on heel-strike impact to push to the bodyweight as a compensation for the decrease in muscle power during propulsion at toe-off. This study among other presented work in the field of VGRF processing forms methods that could be implemented in wearable devices to assess and track runners’ gait as a part of sports performance analysis, rehabilitation phase tracking and classification of healthy vs. unhealthy gait.

The glycine receptor (GlyR) is a ligand-gated ion channel member of the cys-loop receptor superfamily, responsible for inhibitory neurotransmission in the brain and spinal cord. Both glycine and the partial agonist taurine act as endogenous ligands of the GlyR. Taurine-activated GlyR may have a role in the rewarding effects of drugs of abuse, such as ethanol. As a partial agonist, taurine has a decreased efficacy relative to glycine, resulting in a decreased maximum response. We investigated the effects of ethanol, anesthetics, inhalants, and zinc to determine if these allosteric modulators could increase the efficacy of the taurine-activated GlyR. Whole cell recordings of wild type GlyR revealed that each of the allosteric modulators potentiated currents generated by saturating concentrations of taurine but not glycine, implying an increase in efficacy. Zinc is found at GlyR-potentiating concentrations throughout the nervous system, so we examined the combinatorial effects of these allosteric modulators with zinc to mimic in vivo conditions. Whole cell recordings revealed that zinc potentiation of saturating taurine-generated currents decreased further potentiation by another allosteric modulator, indicating no synergistic effects on efficacy. We next investigated the actions of ethanol and isoflurane on the taurine-activated GlyR at the single channel level, finding that both allosteric modulators stabilized the channel open state, increasing the efficacy of the taurine-activated GlyR. We previously identified a mutation in the ligand-binding domain of the GlyR (D97R) that produces spontaneously activating channels, on which taurine has increased efficacy. We identified a residue, R131, as a possible binding partner of D97 in forming an electrostatic interaction that holds the channel in the closed state. We found that disruption of this interaction results in greatly increased taurine efficacy, indicating that efficacy for partial agonists may be determined by agonist ability to break this bond early in the activation process following binding. Thus we find differential mechanisms of allosteric modulation and efficacy determinations for the GlyR when activated by taurine vs. glycine. / text

The glycine receptor (GlyR) is a ligand-gated ion channel member of the cys-loop receptor superfamily, responsible for inhibitory neurotransmission in the brain and spinal cord. Both glycine and the partial agonist taurine act as endogenous ligands of the GlyR. Taurine-activated GlyR may have a role in the rewarding effects of drugs of abuse, such as ethanol. As a partial agonist, taurine has a decreased efficacy relative to glycine, resulting in a decreased maximum response. We investigated the effects of ethanol, anesthetics, inhalants, and zinc to determine if these allosteric modulators could increase the efficacy of the taurine-activated GlyR. Whole cell recordings of wild type GlyR revealed that each of the allosteric modulators potentiated currents generated by saturating concentrations of taurine but not glycine, implying an increase in efficacy. Zinc is found at GlyR-potentiating concentrations throughout the nervous system, so we examined the combinatorial effects of these allosteric modulators with zinc to mimic in vivo conditions. Whole cell recordings revealed that zinc potentiation of saturating taurine-generated currents decreased further potentiation by another allosteric modulator, indicating no synergistic effects on efficacy. We next investigated the actions of ethanol and isoflurane on the taurine-activated GlyR at the single channel level, finding that both allosteric modulators stabilized the channel open state, increasing the efficacy of the taurine-activated GlyR. We previously identified a mutation in the ligand-binding domain of the GlyR (D97R) that produces spontaneously activating channels, on which taurine has increased efficacy. We identified a residue, R131, as a possible binding partner of D97 in forming an electrostatic interaction that holds the channel in the closed state. We found that disruption of this interaction results in greatly increased taurine efficacy, indicating that efficacy for partial agonists may be determined by agonist ability to break this bond early in the activation process following binding. Thus we find differential mechanisms of allosteric modulation and efficacy determinations for the GlyR when activated by taurine vs. glycine. / text

ITC/USA 2013 Conference Proceedings / The Forty-Ninth Annual International Telemetering Conference and Technical Exhibition / October 21-24, 2013 / Bally's Hotel & Convention Center, Las Vegas, NV / The flight test mission services need higher data rates due to increased system complexity and the need for more accurate, higher rate, and better data acquisition. The existing L or S band frequency spectrum allocation was a limiting factor to meet this increased data rate requirement. The World Radio-communication Conference (WRC 2007) attributed new additional frequency spectrum allocations in the C band for Aeronautical Mobile Telemetry (AMT). The international flight test community has taken this opportunity to immediately take advantage of the new C-band range 5091-5250MHz. This paper presents the multi-band feed product designed by the RF & Antenna Laboratory of ZODIAC DATA SYSTEMS company. This feed is foreseen to be used in prime focus configuration on any diameter parabola dish providing telemetry and tracking channels in three L, S, and C bands. Here, are described the concept and the technology achieved taking into consideration the performance and industrial constraints. Moreover, this contribution focuses on the electromagnetic simulations of radiating elements, the feed network and RF system integration. This paper is structured as follows: firstly, the objectives and the motivation for developing a prime focus feed which works in L, S, C bands are presented. In particular, the market constraints and approach to find the best solution satisfying the feed RF requirements, and mechanical constraints, such as weight, size and cost, are discussed. The second section describes the 5 step development cycle: principle and technology, design of the telemetry channels and tracking function, cohabitation of the different radiating elements, and problems of the channels isolations. The third section discusses the performance achieved using electromagnetic simulations. The fourth section talks about the integration of RF system feed. The paper concludes by discussing future work using the same concept that is applied to other telecommunication or telemetry frequency bands.

No description available.

Proton channels are essential for many of the processes of life. The influenza A viral protein M2 is responsible for sensing the conditions necessary for viral RNA release. The proton-translocating FoF1 ATPase (ATP synthase) uses a proton gradient to drive adenosine triphosphate (ATP) synthesis. We have directly measured proton uptake in vesicles containing reconstituted M2 or FO by monitoring external pH after addition of valinomycin to vesicles with 100-fold diluted external [K+]. This proton flux assay was utilized to quantify proton flux through single M2 and Fo channels. Contrary to previous reports, proton uptake by M2 was not significantly altered by acidification of the extravesicular pH. We conclude that pH only weakly affects proton flux through M2 in the pH range of 5.4 - 7.0. Theoretical analysis utilized for such vesicle uptake assays illuminates the appropriate time scale of the initial slope and an important limitation that must be placed on inferences about channel ion selectivity. The rise in pH over 10 seconds after ionophore addition yielded time-averaged single channel conductances of 0.35±0.2 aS and 0.72±0.4 aS at pH 5.4 and 7.0 respectively. Such a low time-average conductance implies that M2 is only conductive 10^-6 to 10^-4 of the time. M2 selectivity for hydrogen over potassium is ~10^7. Fo translocates protons across membranes, converting electrochemical energy to rotational inertia. Previous experiments have been partially confounded by a contaminating channel, CL, which co-purifies with Fo and leaks cations. CL activity is shown to not decrease following deletion of the previously uncharacterized yraM open reading frame of E. coli. Fo purified from a deletion strain lacking yraM is just as active as Fo purified from the wild-type strain. Using Fo from the deletion strain, the single-hit hypothesis of DCCD inhibition of passive proton flux through Fo was examined. A DCCD-induced reduction in ATP synthase activity correlates with a reduction in the total initial slope, the number of functional Fo per µg protein, and the single channel proton flux. At least 2 DCCD per Fo are required to totally inactivate passive proton flux. M2 and Fo have similar single channel conductances but different open probabilities.

A radio direction finding (DF) system is an antenna array and a receiver arranged in a combination to determine the azimuth angle of a distant emitter. Basically, all DF systems derive the emitter location from an initial determination of the angle-of-arrival (AOA). Radio direction finding techniques have classically been based on multiple-antenna systems employing multiple receivers. Classic techniques such as MUSIC [1][2] and ESPRIT use simultaneous phase information from each antenna to estimate the angle-of-arrival of the signal of interest. In many scenarios (e.g., hand-held systems), however, multiple receivers are impractical. Thus, single channel techniques are of interest, particularly in mobile scenarios. Although the amount of existing research for single channel DF is considerably less than for multi-channel direction finding, single channel direction finding techniques have been previously investigated. Since many of the single channel direction finding techniques are older analog techniques and have been analyzed in previous work, we will investigate a new single channel direction finding technique that takes specific advantage of digital capabilities. Specifically, we propose a phase-based method that uses a bank of Phase-Locked Loops (PLLs) in combination with an eight-element circular array. Our method is similar to the Pseudo-Doppler method in that it samples antennas in a circular array using a commutative switch. In the proposed approach the sampled data is fed to a bank of PLLs which track the phase on each element. The parallel PLLs are implemented in software and their outputs are fed to a signal processing block that estimates the AOA. This thesis presents the details of the new Phase-Locked Loop (PLL) algorithm and compares its performance to existing single channel DF techniques such as the Watson-Watt and the Pseudo-Doppler techniques. We also describe the implementation of the PLL algorithm on a DRS Signal Solutions, Incorporated (DRS-SS) WJ-8629A Software Definable Receiver with Sunrise™ Technology and present measured performance results. / Master of Science

Wireless communication is facing an increasingly severe spectrum scarcity problem. Hybrid free space optical (FSO)/ millimetre wavelength (MMW) radio frequency (RF) systems and cognitive radios are two candidate solutions. Hybrid FSO/RF can achieve high data rate transmission for wireless back haul. Cognitive radio transceivers can opportunistically access the underutilized spectrum resource of existing systems for new wireless services. In this work we carry out accurate performance analysis on these two transmission techniques. In particular, we present and analyze a switching based transmission scheme for a hybrid FSO/RF system. Specifically, either the FSO or RF link will be active at a certain time instance, with the FSO link enjoying a higher priority. We consider both a single threshold case and a dual threshold case for FSO link operation. Analytical expressions are obtained for the outage probability, average bit error rate and ergodic capacity for the resulting system. We also investigate the delay performance of secondary cognitive transmission with interweave implementation. We first derive the exact statistics of the extended delivery time, that includes both transmission time and waiting time, for a fixed-size secondary packet. Both work-preserving strategy (i.e. interrupted packets will resume transmission from where interrupted) and non-work-preserving strategy (i.e. interrupted packets will be retransmitted) are considered with various sensing schemes. Finally, we consider a M/G/1 queue set-up at the secondary user and derive the closed-form expressions for the expected delay with Poisson traffic. The analytical results will greatly facilitate the design of the secondary system for particular target application. / Graduate

Ionotrope Glutamatrezeptoren steuern exzitatorische Prozesse im Gehirn. Der AMPA-Rezeptor ist der schnellste Glutamatrezeptor und reguliert die Signaltransduktion in hochfrequenten Bereichen. Um die Konformationen des Rezeptors für die Aktivierung aufzuschlüsseln, wurden die Ligandenbindedomänen (LBD), mit künstlichen Metallbrücken verlinkt. Die tetramerische LBD-Schicht hat mehrere Freiheitsgrade. Sie reichen vom Schließen der LBD durch Ligandenbindung, bis hin zu den verschiedenen Konformationsmöglichkeiten innerhalb des Tetramers. Die bereits publizierte T1-Mutante wurde verlinkt und auf Einzelkanalebene elektrophysiologisch untersucht. Anschließend wurde T1 mit einer Mutante (DKD-3H) verglichen die durch molekulardynamische Simulationen identifiziert wurde. Die Eigenschaften von T1 und DKD-3H wurden mit einem natürlich vorkommenden AMPAR-Linker, namens Con ikot ikot, verglichen. Meeresschnecken der Gattung Conus setzen das Polypeptid zur Fischjagd ein. Zur Analyse wurde eine Software entwickelt, speziell für Ströme von ligandengesteuerten Ionenkanälen mit multiplen Leitfähigkeiten (www.github.com/AGPlested/ASCAM). Durch Verlinkung in T1 konnten drei präaktive Konformationen aufgeschlüsselt werden und die schnelle Aktivierung im sub-Millisekundenbereich verschwindet ganz. Obwohl die Metall-koordinierenden Residuen von T1 und DKD-3H nah beieinander liegen, konnte für DKD-3H nur eine einzelne präaktive Konformation gefunden werden. Es deutet darauf hin, dass die LBD-Schicht von AMPA-Rezeptoren hochdynamisch ist da die geringe Abweichung große Auswirkungen auf den Phänotypen des Rezeptors hat. LBD-Verlinkung mit Con-ikot-ikot ergab einen EC50 von ~5 nM. Alle drei Verlinkungsarten resultierten in einer reduzierten Offenwahrscheinlichkeit. Einzelkanalanalysen von T1 und Con-ikot-ikot-gebundenen AMPA-Rezeptoren unterstützen die Hypothese, dass die veränderten Phänotypen aus dem Wechselspiel der LBDs innerhalb der LBD-Schicht resultieren. / Ionotropic glutamate receptors (iGluRs) mediate excitatory neurotransmission in the mammalian brain. The AMPA-type receptor is the fastest iGluR member, activating at the sub-millisecond time scale. In this study, ligand-binding domains (LBDs), where AMPAR activation is initialised, were cross-linked with artificially introduced metal bridges to trap and investigate conformational states of the receptor before- and during activation. The tetrameric LBD layer has multiple degrees of freedom, from closure of individual clamshells and their conformational arrangement within the dimers and the tetramer. The previously studied T1 mutant was cross-linked at the single-channel level and compared to a second cross-linking mutant (DKD 3H) that was predicted on a molecular dynamics approach. T1 and DKD 3H were to the effects of a naturally occurring AMPAR-specific LBD cross-linker (Con ikot ikot) from a fish-hunting snail of the genus Conus. Single-channel recordings were analysed with a newly developed software dedicated to ligand-gated ion channels with conductances in the low pA range and multiple subconductance levels (www.github.com/AGPlested/ASCAM). Trapping of the T1 mutant revealed three pre-active conformational states that were not described for AMPARs before. Fast activation in the sub-millisecond range disappears fully indicating that these conformations proceed too fast in non-restricted wild-type receptors to be resolved. Although the metal-coordinating residues of T1 and DKD 3H are in close proximity, DKD 3H yielded one single pre-active state. A slightly distinct register of the bridge results in largely different phenotypes. Cross-linking with con ikot ikot identified an EC50 of ~5 nM. All three cross-linking approaches reduced open probability. The results support the hypothesis that the altered phenotypes are not a result of singly restricted LBDs but the dynamics of the tetrameric LBD-layer as one unit.