Towards a Principled Integration of Multi-Camera Re-Identification and Tracking through Optimal Bayes Filters

With the rise of end-to-end learning through deep learning, person detectors and re-identification (ReID) models have recently become very strong. Multi-camera multi-target (MCMT) tracking has not fully gone through this transformation yet. We intend to take another step in this direction by presenting a theoretically principled way of integrating ReID with tracking formulated as an optimal Bayes filter. This conveniently side-steps the need for data-association and opens up a direct path from full images to the core of the tracker. While the results are still sub-par, we believe that this new, tight integration opens many interesting research opportunities and leads the way towards full end-to-end tracking from raw pixels.Comment: First two authors have equal contribution. This is initial work into a new direction, not a benchmark-beating method. v2 only adds acknowledgements and fixes a typo in e-mai

Neue Einblicke – Social Media Monitoring in der Stadtplanung

Das Social Web ist ein Kommunikationskanal, der mittlerweile weit verbreitet ist und den man allgemein schon als Standard bezeichnen kann. Vielfach wurde beschrieben, wie Social Media auch in der Raumplanung zur Kommunikation und Partizipation genutzt werden kann (vgl. Habbel, Huber 2008; VHW 2011; Haller, Höffken 2011). Der Stadtplanung von heute bietet sich aufgrund der stetigen Entwicklung von Hard- und Software sowie eines immer komplexer werdenden Internets eine Vielzahl an Instrumenten, um eine erfolgreiche Planung durchzuführen. So ist es heutzutage möglich, die verschiedenen Aufgabenfelder mit digitalen Werkzeugen zu unterstützen und zu bearbeiten. Ein Beispiel ist der Einsatz von Social Media im Kontext der Bürgerbeteiligung. Um hierbei genauere Analysen des Nutzerverhaltens vornehmen zu können, bietet sich ein Einsatz von Monitoring-Tools wie bspw. Google Analytics an. Dabei steht die Möglichkeit, noch präziser auf die Interessen und Anregungen der Nutzer einzugehen, um eine gezieltere Kommunikation zu erreichen, im Fokus des Interesses (von Dobeneck, 2012). Ziel dieses Papers ist es, in Erfahrung zu bringen, wie der Einsatz einer begleitenden Social Media Strategie aussehen kann und welcher Mehrwert sich für die Stadtplanung erzielen lässt. Nach einem einführenden Teil, werden die Grundlagen von Social Media und der Mehrwert digitaler Instrumente in der Stadtplanung aufgezeigt. Zentrales Element des Papers sind die Ergebnisse aus der Untersuchung eines Praxisbeispiels – eines Weblogs für ein Stadtentwicklungsprojekt. Basierend auf den dort gewonnen Daten werden Erkenntnisse bezüglich möglicher Analysen und Auswertungen, aber auch Grenzen und Hindernissen aufgezeigt. Aufgrund dieser praxisnahen Analyse werden die allgemeinen Erkenntnisse und der Nutzen für einen Einsatz in der Stadtplanung skizziert, wodurch sich konkrete Handlungsempfehlungen ableiten lassen. Ebenfalls werden mögliche Gefahren dargestellt, welche eine Erhebung von nutzergenerierter Daten im Bezug zum Datenschutz, bzw. Recht auf Privatsphäre mit sich bringen. Diese kritische Reflektion soll helfen, einer Übereuphorisierung der Datenanalyse entgegenzuwirken, um eine realistische Einschätzung des Anwendungspotentials für die Stadtplanung geben zu können

Energy efficiency of mmWave massive MIMO precoding with low-resolution DACs

With the congestion of the sub-6 GHz spectrum, the interest in massive multiple-input multiple-output (MIMO) systems operating on millimeter wave spectrum grows. In order to reduce the power consumption of such massive MIMO systems, hybrid analog/digital transceivers and application of low-resolution digital-to-analog/analog-to-digital converters have been recently proposed. In this work, we investigate the energy efficiency of quantized hybrid transmitters equipped with a fully/partially-connected phase-shifting network composed of active/passive phase-shifters and compare it to that of quantized digital precoders. We introduce a quantized single-user MIMO system model based on an additive quantization noise approximation considering realistic power consumption and loss models to evaluate the spectral and energy efficiencies of the transmit precoding methods. Simulation results show that partially-connected hybrid precoders can be more energy-efficient compared to digital precoders, while fully-connected hybrid precoders exhibit poor energy efficiency in general. Also, the topology of phase-shifting components offers an energy-spectral efficiency trade-off: active phase-shifters provide higher data rates, while passive phase-shifters maintain better energy efficiency.Comment: Published in IEEE Journal of Selected Topics in Signal Processin

Signature of frustrated moments in quantum critical CePd1−x_{1-x}Nix_xAl

CePdAl with Ce $4f$ moments forming a distorted kagom\'e network is one of the scarce materials exhibiting Kondo physics and magnetic frustration simultaneously. As a result, antiferromagnetic (AF) order setting in at $T_{\mathrm{N}} = 2.7$~K encompasses only two thirds of the Ce moments. We report measurements of the specific heat, $C$, and the magnetic Gr\"uneisen parameter, $\Gamma_{\rm mag}$, on single crystals of CePd$_{1-x}$Ni$_x$Al with $x\leq 0.16$ at temperatures down to 0.05~K and magnetic fields $B$ up to $8$~T. Field-induced quantum criticality for various concentrations is observed with the critical field decreasing to zero at $x_c\approx 0.15$. Remarkably, two-dimensional (2D) AF quantum criticality of Hertz-Millis-Moriya type arises for $x=0.05$ and $x=0.1$ at the suppression of 3D magnetic order. Furthermore, $\Gamma_{\rm mag}(B)$ shows an additional contribution near $2.5$~T for all concentrations which is ascribed to correlations of the frustrated one third of Ce moments.Comment: 5+2 pages with 4+3 figure

Undercoverage of the elderly institutionalized population: The risk of biased estimates and the potentials of weighting

In most social surveys, the elderly institutionalized population is not part of the target population because it is considered as hard-to-reach and hard-to-interview. The deliberate exclusion of institutionalized elderly from survey samples might cause bias, like previous studies investigating institutionalized elderly persons and their transition to institutions implied. We use a Monte Carlo simulation based on cross-national samples of the Survey of Health, Ageing and Retirement in Europe (SHARE) to test whether the noncoverage and undercoverage of the elderly institutionalized population lead to biased estimates. Moreover, we examined to what extent weights could be used to correct for the underrepresentation of the institutionalized population. Our results show that noncoverage leads to biased estimates in two healthrelated variables. With respect to undercoverage, the precision of all estimates is better, especially if weights accounting for the hard-to-survey population are applied

Integrated optics prototype beam combiner for long baseline interferometry in the L and M bands

In the last few years, integrated optics (IO) beam combiners have facilitated the emergence of 4-telescope interferometers such as PIONIER or GRAVITY, boosting the imaging capabilities of the VLTI. However, the spectral range beyond 2.2microns is not ideally covered by the conventional silica based IO. Here, we propose to consider new laser-written IO prototypes made of GLS glasses, a material that permits access to the mid-infrared spectral regime. Our goal is to conduct a full characterization of our mid-IR IO 2-telescope coupler in order to measure the performance levels directly relevant for long-baseline interferometry. We focus in particular on the exploitation of the L and M astronomical bands. We use a dedicated Michelson-interferometer setup to perform Fourier Transform spectroscopy on the coupler and measure its broadband interferometric performance. We also analyze the polarization properties of the coupler, the differential dispersion and phase degradation as well as the modal behavior and the total throughput. We measure broadband interferometric contrasts of 94.9% and 92.1% for unpolarized light in the L and M bands. Spectrally integrated splitting ratios are close to 50% but show chromatic dependence over the considered bandwidths. Additionally, the phase variation due to the combiner is measured and does not exceed 0.04rad and 0.07rad across the band L and M band, respectively. The total throughput of the coupler including Fresnel and injection losses from free-space is 25.4%. The laser-written IO GLS prototype combiners prove to be a reliable technological solution with promising performance for mid-infrared long-baseline interferometry. In the next steps, we will consider more advanced optical functions as well as a fiber-fed input and revise the optical design parameters in order the further enhance the total throughput and achromatic behavior