16 research outputs found
Multifunctional and compact 3D FMCW MIMO radar system with rectangular array for medium-range applications
No full textMiralles-Navarro, E.; Multerer, T.; Ganis, A.; Schoenlinner, B.; Prechtel, U.; Meusling, A.; Mietzner, J.... (2018). Multifunctional and compact 3D FMCW MIMO radar system with rectangular array for medium-range applications. IEEE Aerospace and Electronic Systems Magazine. 33(4):46-54. https://doi.org/10.1109/MAES.2018.160277S465433
Entwicklung eines spektral effizienten OFDM MIMO Radars für zukünftige Mobilitätsanwendungen im städtischen Luftraum
No full textThis thesis presents novel research in the field of OFDM MIMO RadCom
systems for the use in future urban air mobility (UAM) scenarios.
The UAM scenario creates new requirements for sense and avoid as well as
communication systems. Various flying platforms, manned and unmanned,
will soon fly over our cities. Today’s technology and systems cannot provide
means to enable a safe and reliable operation of such air vehicles. Thus, it
is necessary to investigate new technologies, like the OFDM MIMO radar
which enables 3D sense and avoid plus communications in one device.
This thesis presents several new aspects in terms of digital signal processing
and system design including hardware and software.
Concerning the system design, the thesis treats issues like transmit (TX) receive
(RX) antenna crosstalk, and the optimization of the number of virtual
antennas for a larger virtual aperture and thus a higher angular resolution
through real-valued baseband signals. The thesis presents a complete
simulation model including a channel model for OFDM MIMO radar. Furthermore,
it presents a complete hardware, firmware and software design of
an OFDM MIMO radar which was tested indoors and outdoors in various
conditions.
In terms of signal processing, the thesis introduces a novel phase correction
method to improve the dynamic-range of the direction of arrival (DOA) estimation
for OFDM MIMO radars, and it shows the application of Newman
phase sequences to OFDM symbols in order to lower the peak to average
power ratio (PAPR).
Starting from a pure OFDM MIMO radar, the necessary steps towards a
combined RadCom system are explained. Last, a concept for the airspace
integration of several of these systems is presented.
The research presented in this thesis is the result of a cooperation of the Institute
of Microwaves and Photonics Friedrich-Alexander University Erlangen-
N¨urnberg and Airbus Central Research and Technology in Taufkirchen near
Munich, Germany.In dieser Arbeit werden neue wissenschaftliche Erkenntnisse im Bereich der
orthogonal frequency division multiplexing (OFDM) multiple input multiple
output (MIMO) radar and communication (RadCom) Systeme vorgestellt.
Diese Systeme sollen in zukünftigen autonomen Fluggeräten im Bereich der
urbanen Mobilität zum Einsatz kommen.
Das zukünftige Szenario stellt neue Anforderungen an die Systeme der Umfelderkennung
und Kommunikation. Es ist zu erwarten, dass die Dichte
an Fluggeräten im städtischen Luftraum in den nächsten Jahren drastisch
zunehmen wird. Mit aktueller Technik kann der sichere und verlässliche Betrieb
solcher Plattformen nicht garantiert werden. Daher ist es notwendig
neue Technologien zu erforschen, welche es erlauben den Luftraum dreidimensional
zu erfassen und gleichzeitig Daten zu übertragen. Ein mögliche
Lösung stellt das OFDM MIMO Radar- und Kommunikationssystem dar.
Die vorliegende Arbeit präsentiert mehrere neue Aspekte eines solchen Systems,
unter anderem im Bereich der digitalen Signalverarbeitung, der Systemauslegung,
sowie der Hard- und Software.
Im Bereich der Systemauslegung wurde das Übersprechen der Sendeantennen
auf die Empfangsantennen untersucht. Zugleich wurde eine Systemarchitektur
entwickelt, mit der eine möglichst große virtuelle Apertur und daraus
resultierend eine hohe räumliche Auflösung erzeugt werden kann. Als
weiterer Punkt wurden ein Simulations- und Kanalmodell für das OFDM
MIMO Radar entwickelt. Zudem wird das komplette Systemdesign der
Hard-, Firm- und Software des Radars beschrieben, welches in zahlreichen
Versuchen und Messungen im Labor als auch in Außenmessungen getestet
wurde.
Im Bereich der digitalen Signalverarbeitung wird eine neue Phasenkorrekturmethode
vorgestellt. Diese verbessert die Dynamik bei der Richtungsbestimmung.
Außerdem wird gezeigt wie man anhand der Newman Phasensequenz
ein OFDM Radar Signal erhält, welches einen sehr niedrigen Scheitelfaktor
hat.
Ausgehend von einem reinen OFDM Radar, werden die notwendigen Schritte
zu einem kombinierten Radar- und Kommunikationssystem aufgezeigt. Abschließend
wird ein mögliches Konzept präsentiert, wie mehrere dieser Systeme
in einem gemeinsamen Luftraum betrieben werden könnten.
Die vorliegende Dissertation ist aus einer Kooperation des Lehrstuhls für
Hochfrequenztechnik der Friedrich-Alexander Universität Erlangen-Nürnberg
und Airbus Central Research and Technology in Taufkirchen bei München
entstanden
Design and analysis of trials for mosquito control interventions with contamination
No full textThe movement of mosquitoes leads to a contamination of the effect of an intervention targeting mosquito-borne diseases because people living nearby might benefit from a reduced density of infectious mosquitoes. It is usually attempted to avoid these diffuse effects when testing new interventions. In this thesis however, we seek to understand these contamination effects and build the theoretical basis to estimate them since they may provide valuable information about the intervention effectiveness and should be considered.
We use partial differential equations to describe the dynamics of an Aedes aegypti population under a modified male mosquito release on an island to inform the trial design of such an intervention. By invoking optimal control theory, we assess the optimized release strategy under the constraint of a limited availability of modified males to achieve elimination as fast as possible. Our findings show that, to eliminate Aedes aegypti from a single location, the optimal release strategy is to initially release a high number of modified males and to subsequently release fewer mosquitoes proportionally to the decreasing female population. The best approach for elimination on the whole island is to target high mosquito density areas first and then move the focus in both directions along the periphery of the island until all areas have been covered. Sufficient release intensity has to be retained in the already targeted areas throughout this process to prevent reintroduction.
We then shift our focus to the analysis of trials targeting Anopheles mosquitoes. Informed by a model that describes the dispersion of mosquito with Gaussian kernels, we propose a nonlinear random effects model based on a sigmoid function of the distance to the nearest discordant household to analyze cluster randomized trials or stepped wedge cluster randomized trials of malaria interventions. This model approach leads to a closed-form contamination range that quantifies the measurable extent of the contamination. In a simulation study, we find that this approach indeed provides unbiased and precise estimates of effectiveness if an appropriate number of households is not affected by the contamination range. We extend this model to provide an estimate of the intervention effectiveness as a function of the intervention coverage at each household, that we define based on the estimated contamination range.
This methodological development is then applied to three trials of malaria interventions: the Navrongo trial on the use of insecticide treated nets, the SolarMal trial on the impact of mass trapping of mosquitoes with odor-baited traps and the AvecNet trial on the effect of adding pyriproxyfen to long-lasting insecticidal nets. These three trials were conducted in different countries with different settlement patterns and were testing different malaria interventions. In our reanalyses we find that a sigmoid analysis yields a similar estimate of effectiveness compared to what was found in the original analysis. Furthermore, in all three trials the contamination range is around 100 to 200 meters,
which is much less than the maximal distance Anopheles mosquitoes can fly.
For contamination effects to be estimable, the trial must be designed to collect information from zones where contamination is likely. We use the gained insights to give guidance on how to plan trials to allow for contamination and develop algorithmic approaches for cluster construction that allow for cluster boundaries to pass villages and hence enable the estimation of the contamination range. We conclude by connecting the work on the optimized release strategy for modified male mosquitoes with the analysis of trials with contamination by proposing a trial design that accounts for the dispersal of modified males and tests both the short-term effectiveness and the potential for elimination.
The work reported here creates a solid foundation for measuring and understanding the effects of contamination in trials of mosquito-borne diseases. Cluster size can be reduced to the minimum determined by operational factors or contamination effects, without the need for clusters to correspond to separated villages. This reduces the required number of participants in trials of malaria interventions and should lead to more cost-efficient trials and a better understanding of the indirect effects of interventions in protecting nearby nonusers
Modeling the impact of sterile males on an Aedes aegypti population with optimal control
No full textWe use partial differential equations to describe the dynamics of an Aedes aegypti mosquito population on an island, and the effects of a sterile male release. The model includes mosquito movement and an Allee effect to capture extinction events. We apply optimal control theory to identify the release strategy that eliminates the mosquitoes most rapidly, conditional on a limited availability of sterile males. The optimal solution for a single location is to initially release a substantial number of mosquitoes and to subsequently release fewer sterile males proportionally to the decreasing female population. The optimal solution for the whole island is intractable given a constraint on the total daily release of sterile males. The best approximation to the spatial optimal control strategy is to focus on the high mosquito density areas first and then move outwards (in both directions along the periphery of the island), until all areas have been covered, retaining throughout sufficient release intensity to prevent reintroduction in the already cleared areas
Spectrum-efficient real-time OFDM MIMO Radar for moving target detection in medium-range applications
No full text
Additional file 1 of Analysis of contamination in cluster randomized trials of malaria interventions
No full textAdditional file 1 Analysis_CRT.R. R code for a sigmoid random effects model for the analysis of a CRT of malaria prevalence
12 GHz to 40 GHz 0.13-µm SiGe BiCMOS circuits for UWB 3D real-time OFDM MIMO imaging radar applications
No full textAdditional file 2 of Analysis of contamination in cluster randomized trials of malaria interventions
No full textAdditional file 2 simulated_trial.RData. Simulated data file for the R code in Analysis_CRT.R
