Modeling and Mitigation of Wireless Communications Interference for Spectrum Sharing with Radar

Due to both economic incentives and policy mandates, researchers increasingly face the challenge of enabling spectrum sharing between radar and wireless communications systems. In the past eight years, researchers have begun to suggest a wide variety of approaches to radar-communications spectrum sharing, ranging from transmitter design to receiver design, from spatial to temporal to other-dimensional multiplexing, and from cooperative to non-cooperative sharing. Within this diverse field of innovation, this dissertation makes two primary contributions. First, a model for wireless communications interference and its effects on adaptive-threshold radar detection is proposed. Based on both theoretical and empirical study, we find evidence for both Gaussian and non-Gaussian communications interference models, depending on the modeling situation. Further, such interference can impact radar receivers via two mechanisms—model mismatch and boost to the underlying noise floor—and both mechanisms deserve attention. Second, an innovative signal processing algorithm is proposed for radar detection in the presence of cyclostationary, linearly-modulated, digital communications (LMDC) interference (such as OFDM or CDMA) and a stationary background component. The proposed detector consists of a novel whitening filter followed by the traditional matched filter. Performance results indicate that the proposed cyclostationary-based detector outperforms a standard equivalent detector based on a stationary interference model, particularly when the number of cyclostationary LMDC transmitters is small and their interference-to-noise ratio (INR) is large relative to the stationary background

Promoting Pre-service Physics Teachers’ Science Media Literacy

The Science Media Literacy (SML) framework aims to prepare students for the rapidly changing mediascape, where the task of gatekeeping is increasingly transferred to consumers. In this explorative study we reconstructed pre-service physics teachers’ ideas of the communication of science in society and the strategies they apply when examining a scientific claim made in social media. Furthermore, we investigated to what extent SML could be promoted during an intervention. Results indicate that initially held ideas had been challenged and their strategies for dealing with a scientific claim in public were shifting from epistemic to sociological.Peer Reviewe

Statistical Results on the Performance of an Adaptive-Threshold Radar Detector in the Presence of Wireless Communications Interference Revision 1

In an article recently accepted for publication in the IEEE Transactions on Aerospace and Electronic Sys-tems [1], we investigate the problem of specifying interference protection criteria for a radar sharing spectrum with wireless communications. In that paper, we first propose a statistical model for wireless communications interference based on existing interference and clutter models and supported by original simulations. Then we model the statistical effects of such interference on the detection performance of a cell-averaging adaptive-threshold radar detector. While the IEEE paper summarizes the statistical results and plots some representative figures, many additional calculations were computed than could be presented in an IEEE paper. Therefore, this technical report publishes the complete set of statistical results computed, for the interested reader\u27s reference

Serpentine channels: micro -- rheometers for fluid relaxation times

We propose a novel device capable of measuring the relaxation time of viscoelastic fluids as small as 1\,ms. In contrast to most rheometers, which by their very nature are concerned with producing viscometric or nearly-viscometric flows, here we make use of an elastic instability which occurs in the flow of viscoelastic fluids with curved streamlines. To calibrate the rheometer we combine simple scaling arguments with relaxation times obtained from first normal-stress difference data measured in a classical shear rheometer. As an additional check we also compare these relaxation times to those obtained from Zimm theory and good agreement is observed. Once calibrated, we show how the serpentine rheometer can be used to access smaller polymer concentrations and lower solvent viscosities where classical measurements become difficult or impossible to use due to inertial and/or resolution limitations. In the absence of calibration the serpentine channel can still be a very useful comparative or index device.Comment: accepted for for publication in Lab on a chi

Effekte einer Intervention zur Reduktion von Schmerzen auf zwei neuropädiatrischen Stationen

Die Studie beschäftigt sich mit der Thematik, welche Effekte eine Intervention zur Vermeidung von Schmerzen auf zwei neuropädiatrischen Stationen auf die Bewertung des stationären Aufenthaltes durch Eltern und Patienten hat. Unsere Hypothese besagt dabei, dass eine Veränderung des Schmerzmanagements und der daraus folgenden verbesserten Schmerzprävention eine Veränderung der Sichtweise auf den stationären Aufenthalt bewirkt. Insgesamt waren drei Fragestellungen zu beantworten. Zum einen, welche Faktoren die Bewertung des stationären Aufenthaltes beeinflussen und welchen Stellenwert in diesem Zusammenhang schmerzhafte Eingriffe haben. Als zweites wie der Umgang mit schmerzhaften Eingriffen im stationären Rahmen bewertet wird und als letztes, ob es einen Vergleich in den beiden Befragungsgruppen gibt. Es wurden Leitfadeninterviews mit jeweils 10 stationär aufgenommenen Kindern oder deren Eltern zu zwei unterschiedlichen Zeitpunkten (vor und nach einer viermonatigen, strukturierten Implementierungsphase schmerzreduzierender Maßnahmen) durchgeführt, audioaufgezeichnet, transkribiert und anschließend mithilfe qualitativer Inhaltsanalyse ausgewertet. Es zeigte sich dabei, dass die wichtigsten, den stationären Aufenthalt beeinflussenden Faktoren die Kommunikation mit dem Personal, eine möglichst individuelle Betreuung der Patienten und der Umgang mit Schmerzen sind. Im Vergleich der beiden Befragungsgruppen konnte eine Beeinflussung der schmerzbezogenen Aussagen durch die Einführung der Intervention zur Vermeidung von Schmerzen ermittelt werden. Die Post-Interventionsgruppe war durch die Anwendung von schmerzvermeidenden Maßnahmen beim Ablauf der Durchführung von schmerzhaften Prozeduren und mit dem Schmerzmanagement insgesamt zufriedener. Schlussfolgernd kann gesagt werden, dass auf neuropädiatrischen Stationen Kinder mit kognitiven Einschränkungen häufig sind. Die Untersuchung zeigt, dass insbesondere hier eine Intervention zur Optimierung des Schmerzmanagements den stationären Aufenthalt verbessern kann

Geometric scaling of purely-elastic flow instabilities

We present a combined experimental, numerical and theoretical investigation of the geometric scaling of the onset of a purely-elastic flow instability in a serpentine channel. Good qualitative agreement is obtained between experiments, using dilute solutions of flexible polymers in microfluidic devices, and two-dimensional numerical simulations using the UCM model. The results are confirmed by a simple theoretical analysis, based on the dimensionless criterion proposed by Pakdel-McKinley for onset of a purely-elastic instability

Carreiras paralelas : perspectivas dos profissionais que possuem mais de uma carreira

Com a transformação das relações de trabalho das últimas décadas e a mudança da forma como os indivíduos encaram suas trajetórias profissionais, novas configurações de carreira - como as carreiras paralelas – tornaram-se mais frequentes. Porém, esta que tem se mostrado um fenômeno comum, tem sido pouco estudado na academia e pouco endereçado nas organizações. Este trabalho teve como objetivo identificar as perspectivas de profissionais com carreiras paralelas no que se refere a sua motivação, benefícios, dificuldades e fatores de atração, assim como a percepção do comportamento das organizações sobre o assunto. Para esta finalidade, foi feita uma pesquisa qualitativa que teve por instrumento entrevistas com 8 profissionais de diversas combinações de carreira. A análise dos dados aponta à realidade de que as principais motivações destes profissionais são o autodesenvolvimento e a satisfação pessoal, e que percebem o desenvolvimento profissional e a gestão do tempo como fatores consequências importantes decorrentes do paralelismo. Os dados também indicam que tais profissionais consideram a jornada de trabalho e a cultura organizacional como críticos para escolha da melhor organização para se trabalhar enquanto administrador de mais de uma carreira, assim como indicam que a flexibilização da jornada de trabalho e o cultivo de uma cultura mais aberta a inovação e empreendedorismo, são passos que ajudariam na inclusão destas novas configurações contemporâneas de carreira