WiFi emission-based vs passive radar localization of human targets

In this paper two approaches are considered for human targets localization based on the WiFi signals: the device emission-based localization and the passive radar. Localization performance and characteristics of the two localization techniques are analyzed and compared, aiming at their joint exploitation inside sensor fusion systems. The former combines the Angle of Arrival (AoA) and the Time Difference of Arrival (TDoA) measures of the device transmissions to achieve the target position, while the latter exploits the AoA and the bistatic range measures of the target echoes. The results obtained on experimental data show that the WiFi emission-based strategy is always effective for the positioning of human targets holding a WiFi device, but it has a poor localization accuracy and the number of measured positions largely depends on the device activity. In contrast, the passive radar is only effective for moving targets and has limited spatial resolution but it provides better accuracy performance, thanks to the possibility to integrate a higher number of received signals. These results also demonstrate a significant complementarity of these techniques, through a suitable experimental test, which opens the way to the development of appropriate sensor fusion techniques

Impact of beacon interval on the performance of WiFi-based passive radar against human targets

The capability of WiFi-based passive radar to detect, track and profile human targets in both indoor and outdoor environment has been widely demonstrated. This paper investigates the impact of the Beacon Interval (BI) on the passive radar performance. The results of a dedicated acquisition campaign show that both the detection capability and the localization accuracy progressively degrade as the BI increases due to both the reduction of the received beacons and to the intrinsic undersampling of the target motion. Limit values are suggested for practical applications

Short-range passive radar for small private airports surveillance

This paper investigates the effectiveness of a passive radar for enhancing the security level in small airports and private runways. Specifically WiFi transmissions are parasitically exploited to perform detection and localization of non-cooperative targets that can be occupying the runway and the surrounding areas. Targets of interest include light/ultralight aircrafts, vehicles, people and even animals that may intrude onto the runways either intentionally or accidentally. The experimental results obtained by means of an experimental setup developed at SAPIENZA University of Rome prove the successful applicability of the proposed approach for small airports surveillance. © 2016 EuMA

WiFi-based PCL for monitoring private airfields

In this article, the potential exploitation of WiFi-based PCL systems is investigated with reference to a real-world civil application in which these sensors are expected to nicely complement the existing technologies adopted for monitoring purposes, especially when operating against noncooperative targets. In particular, we consider the monitoring application of small private airstrips or airfields. With this terminology, we refer to open areas designated for the takeoff and landing of small aircrafts that, unlike an airport, have generally short and possibly unpaved runways (e.g., grass, dirt, sand, or gravel surfaces) and do not necessarily have terminals. More important, such areas usually are devoid of conventional technologies, equipment, or procedures adopted to guarantee safety and security in large aerodromes.There exist a huge number of small, privately owned, and unlicensed airfields around the world. Private aircraft owners mainly use these “airports” for recreational, single-person, or private flights for small groups and training flight purposes. In addition, residential airparks have proliferated in recent years, especially inthe United States, Canada, and South Africa. A residential airpark, or “fly-in community,” features common airstrips where homes with attached hangars allow owners to taxi from their hangar to a shared runway. In many cases, roads are dual use for both cars and planes.In such scenarios, the possibility to employ low-cost, compact, nonintrusive, and nontransmitting sensors as a way to improve safety and security with limited impact on the airstrips' users would be of great potential interest. To this purpose, WiFi-based passive radar sensors appear to be good candidates [23]. Therefore, we investigate their application against typical operative conditions experienced in the scenarios described earlier. The aim is to assess the capability to detect, localize, and track authorized and unauthorized targets that can be occupying the runway and the surrounding areas

Passive forward scatter radar based on satellite TV broadcast for air target detection: preliminary experimental results

The focus of this paper is on the detection of airborne targets and on the estimation of their velocity by means of passive forward scatter radar systems based on the DVB-S as transmitter of opportunity. Results related to an experimental campaign carried out near “Leonardo Da Vinci” airport (Rome, Italy) are shown. Particularly the Doppler signature spectrogram is analyzed for a single node FSR configuration and time delay techniques are analyzed for a multi-static configuration suitable for velocity estimation. Obtained results clearly show the feasibility of the DVB-S based FSR configuration to reliably detect aircrafts and the effectiveness of the proposed velocity estimation techniques even in the near field area

Finite Density QCD in the Chiral Limit

We present the first results of an exact simulation of full QCD at finite density in the chiral limit. We have used a MFA (Microcanonical Fermionic Average) inspired approach for the reconstruction of the Grand Canonical Partition Function of the theory; using the fugacity expansion of the fermionic determinant we are able to move continuously in the ($\beta -\mu$) plane with $m=0$.Comment: 3 pages, LaTeX, 3 figures, uses espcrc2.sty, psfig. Talk presented by A. Galante at Lattice 97. Correction of some reference

Impulso fraternal: el efecto creación de comercio y mejora de calificaciones de la migración forzada venezolana en plantas manufactureras colombianas

Este trabajo estudia el impacto de un shock masivo de oferta de trabajo calificado en las exportaciones de las empresas manufactureras colombianas. Exploto la variabilidad geográfica y temporal de los asentamientos de los migrantes forzados venezolanos en las áreas sub-nacionales colombianas mediante un enfoque de variables instrumentales de enclave para dar cuenta de la potencial selección en su ubicación. Utilizando datos anuales de aduana entre 2013 y 2019, encuentro que la migración venezolana aumentó el valor de las exportaciones de las empresas manufactureras colombianas, en particular a los países de altos ingresos de la OCDE ubicados en América del Norte y a los países de bajos ingresos. Este efecto fue más grande para las empresas que exportaban menos antes del éxodo (2012). Además, utilizando un detallado panel anual de empresas manufactureras de 2013 a 2019, identifico el posible mecanismo que opera en el mercado de trabajo y genera el efecto creación de comercio: los inmigrantes redujeron los salarios de los obreros y operarios de las empresas exportadoras y les permitieron mejorar la composición de calificación de su mano de obra, es decir, las empresas pudieron contratar trabajadores más compatibles con las exportaciones a destinos desarrollados.Facultad de Ciencias Económica

Composition and Epigenetic Markers of Heterochromatin in the Aphid Aphis nerii (Hemiptera: Aphididae).

A detailed karyotype analysis of the oleander aphid Aphis nerii focusing on the distribution, molecular composition and epigenetic modifications of heterochromatin was done in order to better understand the structure and evolution of holocentric/holokinetic chromosomes in aphids. The female karyotype (2n = 8) consisted of 3 pairs of autosomes and a pair of X chromosomes that were the longest elements in the karyotype and carried a single, terminally located nucleolar organizer region. Males showed 2n = 7 chromosomes due to the presence of a single X chromosome. Heterochromatin was located in the X chromosomes only and consisted of 4 satellite DNAs that have been identified. A. nerii constitutive heterochromatin was enriched in mono-, di- and tri-methylated H3 histones and HP1 proteins but, interestingly, it lacked DNA methylation that was widespread in euchromatic chromosomal regions. These results suggest that aphid heterochromatin is assembled and condensed without any involvement of DNA methylation